Textures: Linear/Nearest labels; prove the filter pass does not resample pixel art (#68)

Dropdown labels are now Linear (default) and Nearest; the stored values
linear/nearest are unchanged, old project files load as before.

e2e 12c-ii measures in Play at camera zoom 1.37 (screen scale 1.434): a
Nearest edge sampled across seven pixels is byte-identical with and without
a neutral Adjust colors shader, and brightness 0.5 on the same path darkens,
so the pass really runs there. New hook __gm.gameRect(id).

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>

src/editor/debugHook.ts

@@ -224,6 +224,7 @@ export function installDebugHook(app: Application, state: EditorState, editor: E
     objectRect: (id: string) => viewport.objectRect(id),
     /** The same for the Game tab – through the camera, so what the player sees. */
     gameScreen: (id: string) => gameView.objectScreen(id),
+    gameRect: (id: string) => gameView.objectRect(id),
     gameCenter: () => centreOf(gameView),
     graph: {
       current: () => graphEditor.currentAssetId,