- Always send a response (even empty) to prevent client timeouts
- Add pandas-stubs to dev dependencies for mypy type checking
- Server now sends newline-terminated response for all commands
This fixes the mypy CI failure. Integration test failures still need
investigation - likely due to event loop blocking when mixing sync/async.
Test connection handling, multiple clients, instrument access across
all three virtual instruments, physics engine integration, and error
handling. Update pytest-asyncio config for v1.x compatibility.