Add multiple features: auth, uploads, queue management, and filters

- Replace email with username for authentication
  - Update User model, schemas, and auth endpoints
  - Update frontend login and register views
  - Add migration to remove email column

- Add multiple track upload support
  - New backend endpoint for bulk upload
  - Frontend multi-file selection with progress
  - Auto-extract metadata from ID3 tags
  - Visual upload progress for each file

- Prevent duplicate tracks in room queue
  - Backend validation for duplicates
  - Visual indication of tracks already in queue
  - Error handling with user feedback

- Add bulk track selection for rooms
  - Multi-select mode with checkboxes
  - Bulk add endpoint with duplicate filtering
  - Selection counter and controls

- Add track filters in room modal
  - Search by title and artist
  - Filter by "My tracks"
  - Filter by "Not in queue"
  - Live filtering with result counter

- Improve Makefile
  - Add build-backend and build-frontend commands
  - Add rebuild-backend and rebuild-frontend commands
  - Add rebuild-clean variants
  - Update migrations to run in Docker

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

backend/app/routers/auth.py

@@ -12,14 +12,6 @@ router = APIRouter(prefix="/api/auth", tags=["auth"])
 
 @router.post("/register", response_model=Token)
 async def register(user_data: UserCreate, db: AsyncSession = Depends(get_db)):
-    # Check if email exists
-    result = await db.execute(select(User).where(User.email == user_data.email))
-    if result.scalar_one_or_none():
-        raise HTTPException(
-            status_code=status.HTTP_400_BAD_REQUEST,
-            detail="Email already registered",
-        )
-
     # Check if username exists
     result = await db.execute(select(User).where(User.username == user_data.username))
     if result.scalar_one_or_none():
@@ -31,7 +23,6 @@ async def register(user_data: UserCreate, db: AsyncSession = Depends(get_db)):
     # Create user
     user = User(
         username=user_data.username,
-        email=user_data.email,
         password_hash=get_password_hash(user_data.password),
     )
     db.add(user)
@@ -44,13 +35,13 @@ async def register(user_data: UserCreate, db: AsyncSession = Depends(get_db)):
 
 @router.post("/login", response_model=Token)
 async def login(user_data: UserLogin, db: AsyncSession = Depends(get_db)):
-    result = await db.execute(select(User).where(User.email == user_data.email))
+    result = await db.execute(select(User).where(User.username == user_data.username))
     user = result.scalar_one_or_none()
 
     if not user or not verify_password(user_data.password, user.password_hash):
         raise HTTPException(
             status_code=status.HTTP_401_UNAUTHORIZED,
-            detail="Invalid email or password",
+            detail="Invalid username or password",
         )
 
     access_token = create_access_token(data={"sub": str(user.id)})