explain an item wherever the UI names one

Every display naming an item now shows that item's production tooltip, not
only the selection panel's chips: the header block stock, the total cost of
a building multi-selection, the remaining scrap of a debris selection, the
icons of every recipe summary, and a blueprint card's cost.

ItemTooltip moves out of the selection panel and takes an
ItemTooltipContext of its own -- an item is named all over the UI, and the
panel's context carries visuals and a debug flag no tooltip reads. A
recipe line wraps each icon with its amount so the pair can be pointed at
as one statement, and attaches tooltips only where asked: a module button
and the item tooltip itself draw the same line and stay silent.

Hover only wherever the display sits on something the player clicks, whose
click is not free to explain. Note that a recipe line on an option button
can no longer be transparent to the mouse -- Qt never looks inside a
transparent widget for the cursor -- so it relies on press propagation to
keep picking the option.

The header block stock loses world.building_blocks_tooltip, showing what
every other block icon shows instead. The Expand button keeps no tooltip:
its cost is painted into its face with nowhere to hang one, and the button
is due to be removed.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Ne3mejABZoLWKLh8fgpM3x

docs/requirements.md

@@ -381,7 +381,7 @@ Any ship, module, building, or assembler recipe id that appears in no unlock gro
 
   Each option additionally displays a vertical list of recipe lines labeled "Unlocks recipes:", showing which miner and assembler recipes would newly become implicitly unlocked (REQ-LOCK-IMPLICIT) if this option were selected — specifically, the miner recipes and implicitly-gated assembler recipes that are not currently implicitly unlocked but would become so after applying this option's effect. To compute this, all `materials` of the group's granted ship and module schematics are added to the base set per REQ-LOCK-IMPLICIT step 1a, and the output items of the group's granted assembler recipes are added per step 1b, before recomputation.
 
-  Each recipe is shown as a **recipe line** of the same two-row card the item production tooltip uses (REQ-UI-ITEM-TOOLTIP): the icon of the building that runs it (REQ-UI-BUILD-ICON) and the recipe's name — by its `id`, using the same display convention as the assembler recipe-selection dialog — on the first row, and the recipe drawn as the recipe summary draws it (REQ-UI-RECIPE-SUMMARY) on the second. The lines are sorted alphabetically by recipe name. The line says everything there is to say about the recipe, so nothing in this list carries a tooltip describing it, as in the selection dialog (REQ-UI-SELECT-OPTIONS); the items the line names do explain themselves on hover, the click belonging to the option the player is choosing (REQ-UI-ITEM-VALUE-TOOLTIP). If no recipes would be newly unlocked, the list shows "None".
+  Each recipe is shown as a **recipe line** of the same two-row card the item production tooltip uses (REQ-UI-ITEM-TOOLTIP): the icon of the building that runs it (REQ-UI-BUILD-ICON) and the recipe's name — by its `id`, using the same display convention as the assembler recipe-selection dialog — on the first row, and the recipe drawn as the recipe summary draws it (REQ-UI-RECIPE-SUMMARY) on the second. The lines are sorted alphabetically by recipe name. The line says everything there is to say about the recipe, so nothing in this list carries a tooltip describing it, as in the selection dialog (REQ-UI-SELECT-OPTIONS); the items the line names do explain themselves, on hover or click: the card is not itself clicked, the option being taken with the button beneath it (REQ-UI-ITEM-VALUE-TOOLTIP). If no recipes would be newly unlocked, the list shows "None".
 
   **The dialog cannot be dismissed.** Clicking an option is the only thing that closes it: it has no close button, no Cancel, neither Escape nor Q dismisses it, and a click outside it does nothing (REQ-UI-DIALOG-DISMISS). The drop is a reward the player has earned by destroying the station set, and every way out of the dialog would have to either forfeit it or pick an option the player did not — so there is no way out but choosing. The dialog is modal and the game is paused meanwhile, so nothing is waiting on the decision.
 
@@ -445,13 +445,13 @@ Several UI elements carry a tooltip: the header bar's artifact count (REQ-UI-ART
 - REQ-UI-TOOLTIP-DISMISS: A tooltip stays visible until the pointer leaves **both the tooltip and the element it belongs to**, however it was triggered. It does **not time out**: there is no display duration after which it vanishes on its own, so a tooltip listing several recipe lines (REQ-UI-ITEM-TOOLTIP) can be read at whatever pace the player needs. The tooltip is itself part of the area that keeps it open — moving the pointer off the element and onto the tooltip does not hide it — which is what fixes where it is placed: its **top-left corner sits at the pointer**, at the position the pointer had the moment the tooltip was triggered. The pointer therefore starts on the tooltip's own corner and reaches the rest of it without crossing a gap. A tooltip that would run off the screen is pushed back onto it, which only moves it further over the pointer. Once the pointer is outside both, the tooltip hides. Nothing else dismisses it, and nothing else needs to: a click elsewhere is a click the pointer has already travelled to, so the tooltip is gone before it lands.
 - REQ-UI-ITEM-VALUE-TOOLTIP: **Wherever the UI names an item, that spot explains the item.** An item is named by its icon, and it is named in three forms (REQ-UI-ITEM-ICON): as an **item chip**, as a **value** — a number followed by the bare inline icon standing in for the item's name — and as an **icon on its colored square within a recipe summary** (REQ-UI-RECIPE-SUMMARY), each with its per-cycle amount. All three show that item's production tooltip (REQ-UI-ITEM-TOOLTIP). The player can therefore ask what an item is wherever it is named, rather than only where it happens to be drawn as a chip.
 
-  The **whole value carries the tooltip** — the amount and the icon together, in every form: the two are one statement, and an icon alone is a target no taller than a line of text. Nothing else on the line is part of it: the caption beside a value (`Remaining`, `Total cost`) describes the number rather than the item, and a recipe summary's arrow, separators and cycle time belong to no item at all. None of these displays has a click action of its own, so a click shows the tooltip at once, as it does on a chip (REQ-UI-TOOLTIP-TRIGGER). This covers the header bar's building blocks stock (REQ-UI-BLOCKS-ICON), the building multi-selection's total cost (REQ-UI-MULTI-SELECTION), the remaining scrap of the debris panel and the field multi-selection (REQ-UI-DEBRIS-PANEL, REQ-UI-FIELD-MULTI-SELECTION), and every input and output icon of the selection panel's recipe summary, a Shipyard's schematic materials included (REQ-UI-RECIPE-SUMMARY). For a value it holds whether or not the icon file exists: where a missing icon leaves the fallback text (`Stock: <n> Blocks`, `Scrap remaining`), the value still states an amount of an item and still explains it.
+  The **whole value carries the tooltip** — the amount and the icon together, in every form: the two are one statement, and an icon alone is a target no taller than a line of text. Nothing else on the line is part of it: the caption beside a value (`Remaining`, `Total cost`) describes the number rather than the item, and a recipe summary's arrow, separators and cycle time belong to no item at all. None of these displays has a click action of its own, so a click shows the tooltip at once, as it does on a chip (REQ-UI-TOOLTIP-TRIGGER). This covers the header bar's building blocks stock (REQ-UI-BLOCKS-ICON), the building multi-selection's total cost (REQ-UI-MULTI-SELECTION), the remaining scrap of the debris panel and the field multi-selection (REQ-UI-DEBRIS-PANEL, REQ-UI-FIELD-MULTI-SELECTION), every input and output icon of the selection panel's recipe summary, a Shipyard's schematic materials included (REQ-UI-RECIPE-SUMMARY), and the layout configuration dialog's build cost line, which states a ship's materials in that same form (REQ-MOD-UI-DIALOG). For a value it holds whether or not the icon file exists: where a missing icon leaves the fallback text (`Stock: <n> Blocks`, `Scrap remaining`), the value still states an amount of an item and still explains it.
 
   **An item named on something that already carries a tooltip of its own carries none.** One display shows one tooltip, and the one it was given for its own sake is the one that wins: the building block cost on a build button says nothing about blocks, because the button is there to explain the building (REQ-UI-BUILD-COST, REQ-UI-BUILD-TOOLTIP). The module selection buttons are excluded on the same ground even though a module without a `modules.toml` description leaves its button silent (REQ-MOD-UI-DIALOG, REQ-MOD-UI-MODULE-TOOLTIP): the button is a described control by design, and whether one module happens to carry the text is a gap in the config rather than a decision about the UI — the same material icon must not explain itself on one button and not on the one beside it.
 
-  **Everywhere else the item is explained, on a clickable control or not**: the asteroid expansion button's cost (REQ-UI-EXPAND-BUTTON), the blueprint cards' costs (REQ-UI-BLUEPRINT-CARD), the recipe summaries on the selection dialog's option buttons (REQ-UI-SELECT-OPTIONS), and the recipe lines on the unlock-choice dialog's options (REQ-DEF-SCHEMATIC-DROP). These controls say what they do and nothing about the items they name, and the two answers do not compete: an option button says what a recipe makes, an item tooltip says where an input comes from.
+  **Everywhere else the item is explained, on a clickable control or not**: the asteroid expansion button's cost (REQ-UI-EXPAND-BUTTON), the blueprint cards' costs (REQ-UI-BLUEPRINT-CARD), the recipe summaries on the selection dialog's option buttons (REQ-UI-SELECT-OPTIONS), and the recipe lines of the unlock-choice dialog's options (REQ-DEF-SCHEMATIC-DROP). These say what they do and nothing about the items they name, and the two answers do not compete: an option button says what a recipe makes, an item tooltip says where an input comes from.
 
-  **On a clickable control the tooltip shows on hover only.** The click belongs to the control — it buys the expansion, picks the blueprint, selects the recipe, takes the unlock — so it cannot also be the gesture that explains (REQ-UI-TOOLTIP-TRIGGER). A click shows the tooltip at once only where the item is named on something with no click action of its own: an item chip, a value in a row, the selection panel's recipe summary.
+  **On a clickable control the tooltip shows on hover only.** The click belongs to the control — it buys the expansion, picks the blueprint, selects the recipe — so it cannot also be the gesture that explains (REQ-UI-TOOLTIP-TRIGGER). A click shows the tooltip at once wherever the item is named on something with no click action of its own: an item chip, a value in a row, the selection panel's recipe summary, and the recipe lines of an unlock-choice option, whose card is chosen through a button of its own rather than by being clicked (REQ-DEF-SCHEMATIC-DROP).
 
   **An item named inside a tooltip carries none either.** The recipe lines of the item production tooltip name items as a recipe summary does, but a tooltip opened from a tooltip would replace the one being read, since only one is ever on screen and the pointer holds up only what it rests on (REQ-UI-TOOLTIP-TRIGGER, REQ-UI-TOOLTIP-DISMISS).