feat(web): render bgm setups as a 3D table

Wire the tabletop library into the setup detail route: seed the store
from the setup, resolve the surface mount tree, and render world and HUD
surfaces. Add serializedToPackage to convert the vite-emitted package.

packages/tabletop/src/package.ts

@@ -0,0 +1,16 @@
+/**
+ * Convert a serialized package (plain objects, as emitted by the bgm vite
+ * plugin) into a `Package` (Maps). Consumers that load a package from
+ * `virtual:bgm/*` get the serialized form; the tabletop components take the
+ * `Package` form.
+ */
+import type { Package, SerializedPackage } from '@tts/bgm';
+
+export function serializedToPackage(serialized: SerializedPackage): Package {
+  return {
+    meta: serialized.meta,
+    parts: new Map(Object.entries(serialized.parts)),
+    surfaces: new Map(Object.entries(serialized.surfaces)),
+    setups: new Map(Object.entries(serialized.setups)),
+  };
+}