This large PR modernizes the backend of the app:
- Python Dependency Management: Poetry → uv
- Object Storage for local dev: MinIO (now unmaintained) → RustFS
- Makefile Target Standardization to align with other LaSuite repos
- Internationalization Removal on backend: we only care about i18n on the frontend
- Backend dependencies upgrade
This adds an intermediate Postgres-backed queue for inbound messages, that
allows us to run filters like spam processing before inserting messages in their
final storage (soon to be object storage). Also include misc. refactorings.