feat(studio): FixtureProvider — sample data populates the 2-D panels

Task 4 of the UI Studio plan: adds SampleData (static ClientObjectTable
builder with a synthetic player, 6 loose items, 2 side bags, and 3 equipped
pieces) and FixtureProvider (switches on layoutId and calls the production
controller Bind methods — VitalsController, ToolbarController,
InventoryController — so the studio previews panels with plausible data
instead of empty widgets).

Icon ids approach: raw-resolve stub — resolves the base iconId via
RenderStack.ResolveChrome and returns the GL handle directly. This is v1
(single-layer icon); the full 5-layer IconComposer composite is a live-game
concern, not a layout-preview concern.

StudioWindow wires FixtureProvider.Populate after _source.Load; the
ClientObjectTable is stored on _objects so controller event subscriptions
(ObjectAdded/ObjectMoved) remain live for the window's lifetime.

4 new FixtureProviderTests (SampleTable_hasPackContents,
SampleTable_hasWeaponAndArmor, SampleTable_hasEquippedItems,
SampleTable_hasSideBags) — all pass. Full App suite: 602 passed / 2
skipped (pre-existing) / 0 failed. Build green.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/AcDream.App/Studio/FixtureProvider.cs

@@ -0,0 +1,114 @@
+using AcDream.App.Rendering;
+using AcDream.App.UI;
+using AcDream.App.UI.Layout;
+using AcDream.Core.Items;
+using AcDream.Core.Net.Messages;
+
+namespace AcDream.App.Studio;
+
+/// <summary>
+/// Populates a loaded panel with sample data by calling the production
+/// controller Bind methods against <see cref="SampleData"/>.
+///
+/// <para>
+/// The studio is intentionally thin — there is no live game session, no
+/// server connection, and no network. FixtureProvider bridges that gap by
+/// feeding static fixtures (vitals percentages, a fake inventory, empty
+/// shortcut lists) so the bound widgets show plausible state instead of
+/// empty zeroes.
+/// </para>
+///
+/// <para>
+/// <b>IconIds approach:</b> raw-resolve stub — resolve the base <c>iconId</c>
+/// via <see cref="RenderStack.ResolveChrome"/> and return the GL handle
+/// directly. This is intentionally simpler than GameWindow's full
+/// <see cref="IconComposer"/> (5-layer composite). The raw icon is enough
+/// to confirm the grid cells draw something in the studio; the full
+/// compositor is the live-game concern, not the layout preview concern.
+/// </para>
+/// </summary>
+public static class FixtureProvider
+{
+    /// <summary>
+    /// Populate <paramref name="layout"/> with sample data appropriate for
+    /// <paramref name="layoutId"/>. Calls the production controller Bind
+    /// methods so the panel's widgets drive off the same code path as the
+    /// full game.
+    /// </summary>
+    /// <param name="layoutId">The LayoutDesc dat id used to import the layout.</param>
+    /// <param name="layout">The imported layout whose widgets to populate.</param>
+    /// <param name="stack">The live render stack (for <see cref="RenderStack.ResolveChrome"/>
+    /// and <see cref="RenderStack.VitalsDatFont"/>).</param>
+    /// <param name="objects">A <see cref="ClientObjectTable"/> already seeded by
+    /// <see cref="SampleData.BuildObjectTable"/>.</param>
+    public static void Populate(
+        uint layoutId,
+        ImportedLayout layout,
+        RenderStack stack,
+        ClientObjectTable objects)
+    {
+        switch (layoutId)
+        {
+            case 0x2100006Cu:   // vitals
+                VitalsController.Bind(layout,
+                    healthPct:   () => SampleData.HealthPct,
+                    staminaPct:  () => SampleData.StaminaPct,
+                    manaPct:     () => SampleData.ManaPct,
+                    healthText:  () => "80/100",
+                    staminaText: () => "60/100",
+                    manaText:    () => "90/100");
+                break;
+
+            case 0x21000016u:   // toolbar
+                ToolbarController.Bind(
+                    layout,
+                    objects,
+                    shortcuts:  () => System.Array.Empty<PlayerDescriptionParser.ShortcutEntry>(),
+                    iconIds:    MakeIconIds(stack),
+                    useItem:    _ => { },
+                    combatState: null,
+                    peaceDigits:  null,
+                    warDigits:    null,
+                    emptyDigits:  null,
+                    sendAddShortcut:    null,
+                    sendRemoveShortcut: null);
+                break;
+
+            case 0x21000023u:   // inventory
+                InventoryController.Bind(
+                    layout,
+                    objects,
+                    playerGuid: () => SampleData.PlayerGuid,
+                    iconIds:    MakeIconIds(stack),
+                    strength:   () => 100,
+                    datFont:    stack.VitalsDatFont);
+                break;
+
+            default:
+                // Unknown layout — no-op; the panel renders structurally.
+                break;
+        }
+    }
+
+    // ── Helpers ─────────────────────────────────────────────────────────────
+
+    /// <summary>
+    /// Build the <c>iconIds</c> delegate for toolbar / inventory controllers.
+    ///
+    /// <para>
+    /// Raw-resolve stub: resolve the base <paramref name="iconId"/> (arg 2)
+    /// via <see cref="RenderStack.ResolveChrome"/> and return its GL handle.
+    /// The remaining args (type, underlayId, overlayId, effects) are ignored
+    /// for the studio — a single-layer icon is sufficient for layout preview.
+    /// </para>
+    ///
+    /// <para>This is what the task spec calls "v1 raw-resolve stub".</para>
+    /// </summary>
+    private static Func<ItemType, uint, uint, uint, uint, uint> MakeIconIds(RenderStack stack)
+        => (_, iconId, _, _, _) =>
+        {
+            if (iconId == 0u) return 0u;
+            var (handle, _, _) = stack.ResolveChrome(iconId);
+            return handle;
+        };
+}