Package as 'autohover' with uv run / uvx entry points

Add main.py and a flat-layout hatchling build with a console script (autohover = mission_client:main), replacing tool.uv package=false, so the app runs via 'uv run main.py' and installs via uvx / uv tool install -- matching the sibling Crazyflie projects.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

main.py

@@ -0,0 +1,7 @@
+#!/usr/bin/env python3
+"""Entry point for the autohover Crazyflie mission client."""
+
+from mission_client import main
+
+if __name__ == "__main__":
+    main()