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/index.ts

@@ -11,6 +11,9 @@ export {
 } from './part.js';
 export { resolveAssetUrl, assetUrl, traceImage } from './http.js';
 
+// Serialized package -> Package conversion.
+export { serializedToPackage } from './package.js';
+
 // State store + derived render state.
 export {
   useTabletopStore,

packages/tabletop/src/package.test.ts

@@ -0,0 +1,19 @@
+import { describe, expect, it } from 'vitest';
+import { serializedToPackage } from './package.js';
+
+describe('serializedToPackage', () => {
+  it('converts plain-object maps to Map instances', () => {
+    const serialized = {
+      meta: { id: 'harbor' },
+      parts: { 'token#wood': { type: 'token', id: 'wood' } },
+      surfaces: { 'board#harbor': { type: 'board', id: 'harbor', layout: [] } },
+      setups: { 'game#main': { type: 'game', id: 'main', setup: {} } },
+    };
+    const pkg = serializedToPackage(serialized);
+    expect(pkg.meta.id).toBe('harbor');
+    expect(pkg.parts).toBeInstanceOf(Map);
+    expect(pkg.parts.get('token#wood')).toEqual({ type: 'token', id: 'wood' });
+    expect(pkg.surfaces.get('board#harbor')).toMatchObject({ type: 'board' });
+    expect(pkg.setups.get('game#main')).toMatchObject({ type: 'game' });
+  });
+});

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)),
+  };
+}