feat: Add scene filtering to verticals API

- GET /verticals now supports ?scene= parameter
- Add GET /verticals/scenes endpoint
- Filter verticals by is_active=true

backend/routers/verticals.py

@@ -47,12 +47,51 @@ class BulkVerticalPreferencesCreate(BaseModel):
 # --- Public endpoints ---
 
 @router.get("/", response_model=List[VerticalRead])
-def list_verticals(session: Session = Depends(get_session)):
-    """List all available verticals (bands)"""
-    verticals = session.exec(select(Vertical)).all()
+def list_verticals(
+    scene: str | None = None,
+    session: Session = Depends(get_session)
+):
+    """List all available verticals (bands), optionally filtered by scene"""
+    from models import Scene, VerticalScene
+    
+    if scene:
+        # Filter by scene
+        scene_obj = session.exec(select(Scene).where(Scene.slug == scene)).first()
+        if not scene_obj:
+            raise HTTPException(status_code=404, detail="Scene not found")
+        
+        vertical_ids = session.exec(
+            select(VerticalScene.vertical_id).where(VerticalScene.scene_id == scene_obj.id)
+        ).all()
+        
+        verticals = session.exec(
+            select(Vertical)
+            .where(Vertical.id.in_(vertical_ids))
+            .where(Vertical.is_active == True)
+        ).all()
+    else:
+        verticals = session.exec(
+            select(Vertical).where(Vertical.is_active == True)
+        ).all()
+    
     return verticals
 
 
+class SceneRead(BaseModel):
+    id: int
+    name: str
+    slug: str
+    description: str | None = None
+
+
+@router.get("/scenes", response_model=List[SceneRead])
+def list_scenes(session: Session = Depends(get_session)):
+    """List all scenes (genres)"""
+    from models import Scene
+    scenes = session.exec(select(Scene)).all()
+    return scenes
+
+
 @router.get("/{slug}", response_model=VerticalRead)
 def get_vertical(slug: str, session: Session = Depends(get_session)):
     """Get a specific vertical by slug"""