Add admin account with user management endpoints

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

backend/app/utils/security.py

@@ -17,9 +17,11 @@ def verify_password(plain: str, hashed: str) -> bool:
     return pwd_context.verify(plain, hashed)
 
 
-def create_token(user_id: int) -> str:
+def create_token(user_id: int, admin_id: Optional[int] = None) -> str:
     expire = datetime.now(timezone.utc) + timedelta(minutes=settings.access_token_expire_minutes)
-    payload = {"sub": str(user_id), "exp": expire}
+    payload: dict = {"sub": str(user_id), "exp": expire}
+    if admin_id is not None:
+        payload["admin_id"] = admin_id
     return jwt.encode(payload, settings.secret_key, algorithm=settings.algorithm)
 
 
@@ -32,3 +34,10 @@ def decode_token(token: str) -> Optional[int]:
         return int(user_id)
     except JWTError:
         return None
+
+
+def decode_token_full(token: str) -> Optional[dict]:
+    try:
+        return jwt.decode(token, settings.secret_key, algorithms=[settings.algorithm])
+    except JWTError:
+        return None