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/storage/protocol.py

@@ -0,0 +1,39 @@
+"""Storage abstraction. Default impl is Nextcloud/WebDAV; swap for S3, local FS, etc."""
+
+from __future__ import annotations
+
+from typing import Protocol
+
+
+class FileMetadata:
+    def __init__(self, path: str, etag: str, size: int, content_type: str) -> None:
+        self.path = path
+        self.etag = etag
+        self.size = size
+        self.content_type = content_type
+
+
+class StorageClient(Protocol):
+    async def create_folder(self, path: str) -> None:
+        """Create a folder (and parents) at the given path."""
+        ...
+
+    async def get_file_metadata(self, path: str) -> FileMetadata:
+        """Return metadata for the file at path."""
+        ...
+
+    async def list_folder(self, path: str) -> list[FileMetadata]:
+        """List immediate children of the folder at path."""
+        ...
+
+    async def download(self, path: str) -> bytes:
+        """Download and return the raw bytes of the file at path."""
+        ...
+
+    async def get_direct_url(self, path: str) -> str:
+        """Return a URL for direct access to the file (used for HLS streaming)."""
+        ...
+
+    async def delete(self, path: str) -> None:
+        """Delete a file or folder at path."""
+        ...