fix(loyalty): replace broad exception handlers with specific types and rename onboarding service

- Replace `except Exception` with specific exception types in
  google_wallet_service.py (requests.RequestException, ValueError, etc.)
  and apple_wallet_service.py (httpx.HTTPError, OSError, ssl.SSLError)
- Rename loyalty_onboarding.py -> loyalty_onboarding_service.py to
  match NAM-002 naming convention (+ test file + imports)
- Add PasswordChangeResponse Pydantic model to user_account API,
  removing raw dict return and noqa suppression

Resolves 12 EXC-003 + 1 NAM-002 architecture warnings in loyalty module.

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

app/modules/tenancy/schemas/user_account.py

@@ -56,3 +56,9 @@ class UserPasswordChange(BaseModel):
         if not any(char.isalpha() for char in v):
             raise ValueError("Password must contain at least one letter")
         return v
+
+
+class PasswordChangeResponse(BaseModel):
+    """Response for a successful password change."""
+
+    message: str