fix(app): #348 — cursor switches ride a process-lifetime native cache; the per-flip Win32 handle leak is closed

Silk's per-mouse ICursor recreates the native Win32 cursor on every
Image assignment; a per-frame cursor alternation (the pick cursor
flickering between kinds while hovering an ANIMATED NPC — exactly the
stand-at-a-vendor posture) allocated a fresh USER handle each flip
until CreateCursor died with "Not enough memory" and took the render
loop with it (vendor-gate.log, exit 82 — surfaced as one clean stack
by #343's fix, as designed).

GlfwCursorCache restores retail's own shape: each distinct
MediaDescCursor is created ONCE for the process lifetime
(glfwCreateCursor, rejected media cached as permanent misses) and
switching is an O(1) zero-allocation glfwSetCursor. The AP-72
missing-art standard-cursor fallback rides the same cache
(Arrow/Hand/Crosshair/IBeam; anything else keeps the Silk path).
Graphical hosts attach after the native window exists; tests and
windowless hosts keep the Silk path untouched. RetailCursorManager's
dedup and PlanApplication logic are unchanged.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

src/AcDream.App/Rendering/GameWindow.cs

@@ -996,6 +996,9 @@ public sealed class GameWindow :
             _retailChatVm = retained.Chat;
             _characterSheetProvider = retained.CharacterSheet;
             _frameScreenshots = retained.Screenshots;
+            // #348: cursor switches ride a process-lifetime native cache
+            // instead of Silk's recreate-per-assignment path.
+            retained.Runtime.AttachNativeCursorWindow(_window?.Native?.Glfw ?? 0);
         }
     }