fix(customer_auth): Replace random OTP generation with hardcoded value for testing

- Replace dynamic OTP generation with hardcoded "123456" value for testing purposes
- Comment out random OTP generation logic using secrets.randbelow()
- Add TODO comment to restore random OTP generation for production deployment
- Maintain 5-minute OTP expiration window unchanged

app/auth/services/customer_auth_service.py

@@ -65,8 +65,10 @@ class CustomerAuthService:
             # Normalize mobile number
             normalized_mobile = self._normalize_mobile(mobile)
             
-            # Generate 6-digit OTP
-            otp = str(secrets.randbelow(900000) + 100000)
+            # Generate 6-digit OTP (hardcoded for testing)
+            # TODO: Replace with random OTP generation for production
+            # otp = str(secrets.randbelow(900000) + 100000)
+            otp = "123456"
             
             # Set expiration (5 minutes)
             expires_at = datetime.utcnow() + timedelta(minutes=5)