Polish chat UI and wire flue agent env

- Add chat components (header, composer, conversation, message, thinking response, identity)
- Add chat hooks (use-chat-agent, use-chat-composer)
- Add chat lib (constants, transforms, types)
- Wire agent model config through env (provider, name, api, base url, key, context window, max tokens)
- Refresh web styling and routes

packages/agents/package.json

@@ -7,6 +7,7 @@
     "build": "bun --env-file=../../.env flue build",
     "check-types": "tsc --noEmit",
     "dev": "bun --env-file=../../.env flue dev",
+    "dev:tailscale": "bun --env-file=../../.env flue dev",
     "run": "bun --env-file=../../.env flue run",
     "run:zopu": "bun --env-file=../../.env flue run zopu"
   },