give output-group eligibility one home

The rule that decides whether a group may be picked -- every item it yields
unlocked, the group judged whole because its items are produced together
(REQ-LOCK-OUTPUT-POOL) -- was written out inside rollOutputGroup, where nothing
outside the sim could reach it. It moves next to producesItem and
getProducibleItems in RecipesConfig.h, which is where the recipe-level queries
already shared between lib and ui live.

Deliberately narrow: the helper says whether a group is eligible, not whether
eligibility is asked about at all. rollOutputGroup keeps its own reason for not
asking when a recipe has a single group.

No behaviour change; the pool's end-to-end test still covers the rule and a
direct one now pins the judged-whole semantics.

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

src/lib/config/RecipesConfig.h

@@ -1,6 +1,7 @@
 #pragma once
 
 #include <algorithm>
+#include <functional>
 #include <optional>
 #include <string>
 #include <vector>
@@ -82,6 +83,24 @@ inline bool producesItem(const RecipeDef& recipe, const std::string& itemId)
     return false;
 }
 
+// True when every item this group yields is unlocked. A group is judged whole -- its
+// items are produced together, so one locked item disqualifies the group entirely, since
+// taking it would hand the player a locked item (REQ-LOCK-OUTPUT-POOL).
+//
+// This says whether a group is eligible, not whether eligibility is asked about at all:
+// that is the caller's, because the callers differ. A cycle picking its result does not
+// ask where there is only one group to pick (see ProductionSystem::rollOutputGroup).
+inline bool isOutputGroupUnlocked(
+    const RecipeOutputGroup& group,
+    const std::function<bool(const std::string&)>& isItemUnlocked)
+{
+    for (const RecipeOutput& out : group.items)
+    {
+        if (!isItemUnlocked(out.item)) { return false; }
+    }
+    return true;
+}
+
 struct RecipesConfig
 {
     std::vector<RecipeDef> recipes;