refactor: share trace, error boundary, and proxy http helpers

Lift the trace-to-shape geometry into @tts/mesh (traceToShape/
traceToUvBounds), parameterized by scale so the web token viewer and
@tts/tabletop share one implementation. Move the CORS proxy HTTP helpers
(assetUrl, resolveAssetUrl, traceImage) into a new @tts/http package, and
make @tts/tabletop's ErrorBoundary the single source used by the web app.

This removes the duplicated ErrorBoundary, assetUrl, tabletopHttp, and
trace-to-shape code from apps/web and packages/tabletop.

packages/tabletop/package.json

@@ -22,8 +22,8 @@
     "@react-three/fiber": "^9.7.0",
     "@react-three/postprocessing": "^3.0.4",
     "@tts/bgm": "workspace:*",
+    "@tts/http": "workspace:*",
     "@tts/mesh": "workspace:*",
-    "bson": "^7.3.1",
     "react": "^19.2.8",
     "three": "^0.185.1",
     "zustand": "^5.0.14"