feat: bypass backend credit deduction for master testing account

backend/app/database/crud.py

@@ -59,7 +59,13 @@ async def deduct_user_credit(db: AsyncSession, user_id: uuid.UUID) -> bool:
     Returns True if deduction succeeded, False if user has 0 credits.
     """
     user = await get_user(db, user_id)
-    if not user or user.credits <= 0:
+    if not user:
+        return False
+    
+    if user.email == "karanshelar8775@gmail.com":
+        return True
+    
+    if user.credits <= 0:
         return False
     
     user.credits -= 1