Replace TS game shell with Bevy/Rust client, add auth service, purge legacy archive

- Replace apps/game (TypeScript/Vite/R3F) with a Bevy 0.16 Rust client
  featuring main menu, star map, and flight states
- Add services/auth: Express + better-auth server with SpacetimeDB
  token exchange endpoint
- Delete archive/legacy-static/ (old JS demos, CSS, assets)
- Update docs pages (architecture, gameplay, roadmap, social, overview)
  to reflect Bevy pivot
- Clean up workspace config: remove apps/game from pnpm workspace,
  update dev scripts, tsconfig, and AGENTS.md files
- Add .vscode/settings.json for Rust tooling

tsconfig.base.json

@@ -7,7 +7,7 @@
     "skipLibCheck": true,
     "esModuleInterop": true,
     "allowSyntheticDefaultImports": true,
-    "strict": false,
+    "strict": true,
     "forceConsistentCasingInFileNames": true,
     "module": "ESNext",
     "moduleResolution": "Bundler",