Replace Vercel AI SDK with Anthropic Claude Agent SDK.
Add standalone agent server (packages/agent-server/)
with MCP tools, JWT auth, and SSE streaming. Introduce
bridge API routes (src/app/api/compass/) and custom
SSE hooks (use-agent, use-compass-chat) replacing
useChat. Remove provider.ts, tools.ts, system-prompt.ts,
github-tools.ts, usage.ts, and old agent route.
