feat(marketplace): add marketplace listings API and catalog items CRUD

backend/app/dependencies.py

@@ -53,3 +53,33 @@ async def get_current_user(
 
 
 CurrentUser = Annotated[User, Depends(get_current_user)]
+
+oauth2_scheme_optional = OAuth2PasswordBearer(tokenUrl="/api/auth/login", auto_error=False)
+
+
+async def get_optional_user(
+    token: Annotated[str | None, Depends(oauth2_scheme_optional)],
+    db: Annotated[AsyncSession, Depends(get_db)],
+) -> User | None:
+    """Resolve the JWT bearer token to a User if present and valid, otherwise None."""
+    if not token:
+        return None
+    try:
+        payload = jwt.decode(
+            token, settings.public_pem, algorithms=[settings.ALGORITHM]
+        )
+        user_id: str | None = payload.get("sub")
+        if user_id is None:
+            return None
+        user_id_int = int(user_id)
+    except (JWTError, ValueError, TypeError):
+        return None
+
+    result = await db.execute(select(User).where(User.id == user_id_int))
+    user = result.scalar_one_or_none()
+    if user is None or not user.is_active:
+        return None
+    return user
+
+
+OptionalUser = Annotated[User | None, Depends(get_optional_user)]