Gatekeeper - Door access system

Status: WIP - not prod ready

Dev with nix develop
sync python deps with uv sync
start dev server uv run fastapi dev
Swagger UI @ http://127.0.0.1:8000/docs
start prod server uv run fastapi run

Issues:

• nix run currently broken
• no door state
• no door operations
• card system is dummy until I get hardware