Add end-to-end MCP coverage

[benvinegar]

Summary

• add an automated MCP end-to-end test that starts the local daemon and a real source Hunk TTY session
• connect through the MCP client SDK, wait for session registration, and send a live comment tool call
• assert that the inline note text renders in the captured terminal transcript

Testing

• bun run typecheck
• bun test test/mcp-e2e.test.ts
• bun test
• bun run test:tty-smoke