Initial commit: RehearsalHub POC

Full-stack self-hosted band rehearsal platform:

Backend (FastAPI + SQLAlchemy 2.0 async):
- Auth with JWT (register, login, /me, settings)
- Band management with Nextcloud folder integration
- Song management with audio version tracking
- Nextcloud scan to auto-import audio files
- Band membership with link-based invite system
- Song comments
- Audio analysis worker (BPM, key, loudness, waveform)
- Nextcloud activity watcher for auto-import
- WebSocket support for real-time annotation updates
- Alembic migrations (0001–0003)
- Repository pattern, Ruff + mypy configured

Frontend (React 18 + Vite + TypeScript strict):
- Login/register page with post-login redirect
- Home page with band list and creation form
- Band page with member panel, invite link, song list, NC scan
- Song page with waveform player, annotations, comment thread
- Settings page for per-user Nextcloud credentials
- Invite acceptance page (/invite/:token)
- ESLint v9 flat config + TypeScript strict mode

Infrastructure:
- Docker Compose: PostgreSQL, Redis, API, worker, watcher, nginx
- nginx reverse proxy for static files + /api/ proxy
- make check runs all linters before docker compose build

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

api/src/rehearsalhub/queue/protocol.py

@@ -0,0 +1,28 @@
+"""Job queue abstraction. Swap Redis for any other backend by implementing this Protocol."""
+
+from __future__ import annotations
+
+import uuid
+from typing import Any, Protocol
+
+
+class JobQueue(Protocol):
+    async def enqueue(self, job_type: str, payload: dict[str, Any]) -> uuid.UUID:
+        """Persist job to DB + push UUID onto queue. Returns the job UUID."""
+        ...
+
+    async def dequeue(self, timeout: int = 5) -> tuple[uuid.UUID, str, dict[str, Any]] | None:
+        """Block up to `timeout` seconds for a job. Returns (id, type, payload) or None."""
+        ...
+
+    async def mark_running(self, job_id: uuid.UUID) -> None:
+        """Mark a job as running. Called by the worker when it picks up the job."""
+        ...
+
+    async def mark_done(self, job_id: uuid.UUID) -> None:
+        """Mark a job as successfully completed."""
+        ...
+
+    async def mark_failed(self, job_id: uuid.UUID, error: str) -> None:
+        """Mark a job as failed with an error message. Increments attempt counter."""
+        ...