fix: switch admin auth to HTTPBearer for consistent Swagger UI

Same fix as manager_auth — OAuth2PasswordBearer was showing an OAuth2
form in Swagger instead of a plain Bearer token input, causing
'Not authenticated' when testing via the docs.

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

cloud_backend/auth_utils.py

@@ -2,7 +2,7 @@ from datetime import datetime, timedelta, timezone
 from jose import jwt, JWTError
 from passlib.context import CryptContext
 from fastapi import Depends, HTTPException, status
-from fastapi.security import OAuth2PasswordBearer
+from fastapi.security import HTTPBearer, HTTPAuthorizationCredentials
 from sqlalchemy.orm import Session
 
 from config import settings
@@ -10,7 +10,7 @@ from database import get_db
 from models.admin import Admin
 
 pwd_context = CryptContext(schemes=["bcrypt"], deprecated="auto")
-oauth2_scheme = OAuth2PasswordBearer(tokenUrl="/api/auth/login")
+_bearer = HTTPBearer()
 
 ALGORITHM = "HS256"
 
@@ -29,9 +29,9 @@ def create_access_token(data: dict) -> str:
     return jwt.encode(payload, settings.SECRET_KEY, algorithm=ALGORITHM)
 
 
-def get_current_admin(token: str = Depends(oauth2_scheme), db: Session = Depends(get_db)) -> Admin:
+def get_current_admin(credentials: HTTPAuthorizationCredentials = Depends(_bearer), db: Session = Depends(get_db)) -> Admin:
     try:
-        payload = jwt.decode(token, settings.SECRET_KEY, algorithms=[ALGORITHM])
+        payload = jwt.decode(credentials.credentials, settings.SECRET_KEY, algorithms=[ALGORITHM])
         username: str = payload.get("sub")
         if not username:
             raise HTTPException(status_code=status.HTTP_401_UNAUTHORIZED, detail="Invalid token")