Add MCP Server for agent communication

- Implement MCP server on stdio for agent communication
- Tools: get_next_task, update_task_status, create_branch, create_pull_request, ask_user_question
- Full integration with database (tasks, agents tables)
- Proper error handling and responses
- Add 'mcp' script to package.json

Co-Authored-By: Claude Sonnet 4.5 (1M context) <noreply@anthropic.com>

package.json

@@ -7,6 +7,7 @@
   "scripts": {
     "dev": "bun --watch src/index.ts",
     "start": "bun src/index.ts",
+    "mcp": "bun src/mcp/server.ts",
     "build": "bun build src/index.ts --outdir dist --target bun",
     "db:generate": "drizzle-kit generate",
     "db:migrate": "bun src/db/migrate.ts",