**Refactor Docker and Compose for enhanced compatibility and efficiency**

- Restructured `Dockerfile` to include a dedicated frontend build stage and improved runtime configurations.
- Added new health checks and adjusted environment variables for better container management.
- Updated cron job configurations to leverage `/opt/venv` and align with new paths.
- Refined `docker-compose` files for multi-service setups, including better volume and environment variable handling.
- Migrated `cbwebreader-cron` service setup and improved restart policies across the board.
- Enhanced `.gitea` CI workflow to use updated tools (`uv`), streamline buildx processes, and ensure proper version extraction from metadata.

cbreader/crontab

@@ -1 +1 @@
-*/15 * * * * root /src/.venv/bin/python /src/manage.py scan_comics --settings=cbreader.settings.base
+*/15 * * * * root /opt/venv/bin/python /src/manage.py scan_comics --settings=cbreader.settings.base