give the selection cards their own parts instead of label blobs

The cards were assembled from plain labels carrying whole blocks of text.
Replace those with the widget vocabulary the requirements describe, so a part
means the same thing wherever it appears and a card is a list of parts rather
than a string builder.

The parts, all free of Simulation and GameConfig -- they take prepared values,
and the contents work out what those are:
- StatRow, BarRow, SectionBox: label/value line, captioned fill bar, captioned
  group. The bar is one part for three things: construction progress,
  production progress, and HP.
- ItemChip / ItemChipRow: buffered items as icon, count and sub-line
  (REQ-UI-SINGLE-SELECTION). An input chip carries its per-cycle amount, an
  output chip its count against the buffer capacity. The chips are rebuilt only
  when the set of items changes, so a 30 Hz refresh moves numbers rather than
  widgets.
- RecipeSummaryRow: inputs, arrow, outputs, cycle time (REQ-UI-RECIPE-SUMMARY),
  which is now the panel's only display of the cycle time.
- CountRow, StatusPill, EmptyNote.

Behaviour that changed with them:
- The station card shows damage, range and fire rate as the requirement asks
  (REQ-UI-STATION-STATS-PANEL) rather than the combined DPS it showed before.
- A ship's behaviour moves from a stats row into the card header
  (REQ-UI-SHIP-BEHAVIOR). ShipStatsPanel keeps setBehavior for the balancing
  tool's inspect window, which has no header to put it in.
- A construction site's card shows a progress bar and the "no buffers until
  built" note (REQ-UI-SELECTION-CARD), and now also its recipe summary, since
  that is configuration and a site carries it (REQ-BLD-SITE-CONFIG). Costing a
  shipyard site's schematic needed computeShipyardRequiredMaterials to take a
  stored configuration as well as a live building -- one overload, so the
  module sum still exists once.

ShipStatsPanel is rebuilt on StatRow, BarRow and SectionBox, so the selection
card, the layout dialog's design preview and the balancing tool read alike.
Those three parts are compiled into the balancing target, which does not link
the ui library; keeping them sim-free is what makes that possible, and the
build enforces it.

Build clean, 541 tests pass, app and balancing tool both run with no Qt
warnings. Visual check pending.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01JcReq7hVk4KUPhTDKWAG7K

src/ui/selection/BarRow.h

@@ -0,0 +1,36 @@
+#pragma once
+
+#include <QColor>
+#include <QString>
+#include <QWidget>
+
+class QLabel;
+
+// A caption with its value hard right and a horizontal fill bar beneath it. One part for
+// the three things the panel shows as a proportion: a construction site's progress, a
+// building's production cycle, and the HP of a ship, a station or the HQ
+// (REQ-UI-PRODUCTION-PROGRESS, REQ-UI-SHIP-STATS-PANEL, REQ-UI-STATION-STATS-PANEL,
+// REQ-UI-HQ-PANEL).
+//
+// The caption may be left empty, for a bar whose meaning is already given by the section
+// it sits in.
+class BarRow : public QWidget
+{
+    Q_OBJECT
+
+public:
+    explicit BarRow(const QString& caption, QWidget* parent = nullptr);
+
+    // fraction is clamped to [0, 1]; valueText is shown beside the caption as-is, so a
+    // bar can read "72%" or "340 / 500" as its meaning requires.
+    void setValue(double fraction, const QString& valueText);
+    // Overrides the fill color, which defaults to the palette's highlight.
+    void setFillColor(const QColor& color);
+
+private:
+    class Bar;
+
+    QLabel* m_captionLabel;
+    QLabel* m_valueLabel;
+    Bar*    m_bar;
+};