chore: remove unused deps and declare missing ones

Knip-driven cleanup across all workspaces:

Removed (verified zero imports):
- root: @anthropic-ai/claude-agent-sdk, @modelcontextprotocol/sdk,
  expo, react, react-native, react-dom (duplicates of workspace deps)
- server: @ai-sdk/openai, @deepgram/sdk, express-basic-auth,
  fast-uri, mnemonic-id, tiny-invariant, playwright
- app: @expo/vector-icons, @getpaseo/server,
  @react-navigation/bottom-tabs, @react-navigation/elements,
  base64-js, react-native-css, expo-av, expo-font, expo-symbols,
  expo-web-browser, react-native-permissions,
  react-native-popover-view, react-native-securerandom
- cli: @getpaseo/relay
- desktop: @getpaseo/cli
- relay: @cloudflare/workers-types
- website: tailwindcss (provided by @tailwindcss/vite)

Declared (previously hoisted, now explicit):
- root: @types/ws, playwright, ws (used by scripts/)
- server: @mariozechner/pi-ai, @mariozechner/pi-agent-core
- app: expo-asset, qrcode, @types/qrcode, tiny-invariant,
  @xterm/headless, dotenv, jsdom
- cli: vitest
- desktop: vitest

Also removes the stray `/app.json` (obsolete, overridden by
packages/app/app.config.js).

packages/website/package.json

@@ -28,7 +28,6 @@
     "@types/react": "^19.1.6",
     "@types/react-dom": "^19.1.5",
     "@vitejs/plugin-react": "^4.5.1",
-    "tailwindcss": "^4.1.8",
     "typescript": "^5.9.3",
     "vite": "^7.0.0",
     "vite-tsconfig-paths": "^5.1.4"