Adds tests/integration/test_main_lifespan.py with 5 cases that exercise
the end-to-end main.app lifespan:
- default (no MCP_SERVICES) mounts both services in BUILTIN order
- MCP_SERVICES=files mounts only files
- MCP_SERVICES='' mounts zero
- MCP_SERVICES=bogus raises RuntimeError at startup
- /health on the root app is unaffected by MCP filtering
Tests use TestClient and mock main.init_mcp_server to record mount
calls, since fastapi-mcp's HTTP endpoints 404 for bare GETs regardless
of mount state (the MCP transport requires an initialize handshake
before any tool call). Mocking avoids that coupling.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
