Restructure into pnpm monorepo with game shell, docs, and SpacetimeDB backend

- Restructure flat static prototype into pnpm workspace monorepo
- apps/game: playable shell with R3F 3D scene, HUD, SpacetimeDB connection
- apps/docs: design docs and prototypes
- apps/site: landing page
- packages/ui: shared Button and Panel primitives
- services/spacetimedb: backend module (9 tables, 11 reducers)
- Archive legacy static files to archive/legacy-static/
- Game loop: connect, undock, target, approach, dock, mine, sell
- Add pnpm-workspace.yaml, tsconfig.base.json, spacetime.json

archive/legacy-static/js/state.js

@@ -0,0 +1,30 @@
+window.GDD = window.GDD || {};
+
+/* Simple pub/sub state store — Zustand-like for prototype */
+window.GDD.createStore = function createStore(initialState) {
+  let state = { ...initialState };
+  const listeners = new Set();
+
+  return {
+    getState: () => ({ ...state }),
+    setState: (partial) => {
+      const next = typeof partial === 'function' ? partial(state) : partial;
+      state = { ...state, ...next };
+      listeners.forEach(fn => fn(state));
+    },
+    subscribe: (fn) => {
+      listeners.add(fn);
+      return () => listeners.delete(fn);
+    }
+  };
+};
+
+/* App-level store */
+window.GDD.appStore = window.GDD.createStore({
+  currentPage: 'overview',
+  sidebarCollapsed: false,
+  sidebarOpen: false, // mobile
+  connected: true,
+  playerName: 'Captain Riker',
+  playerCredits: 125000,
+});