feat(loyalty): Google Wallet production readiness — 10 hardening items

- Fix rate limiter to extract real client IP and handle sync/async endpoints
- Rate-limit public enrollment (10/min) and program info (30/min) endpoints
- Add 409 Conflict to non-retryable status codes in retry decorator
- Cache private key in get_save_url() to avoid re-reading JSON per call
- Make update_class() return bool success status with error-level logging
- Move Google Wallet config from core to loyalty module config
- Document time.sleep() safety in retry decorator (threadpool execution)
- Add per-card retry (1 retry, 2s delay) to wallet sync task
- Add logo URL reachability check (HEAD request) to validate_config()
- Add 26 comprehensive unit tests for GoogleWalletService

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

app/modules/loyalty/tasks/wallet_sync.py

@@ -66,20 +66,38 @@ def sync_wallet_passes() -> dict:
 
         google_synced = 0
         apple_synced = 0
+        failed_card_ids = []
 
         for card in cards:
-            try:
-                results = wallet_service.sync_card_to_wallets(db, card)
-                if results.get("google_wallet"):
-                    google_synced += 1
-                if results.get("apple_wallet"):
-                    apple_synced += 1
-            except Exception as e:
-                logger.warning(f"Failed to sync card {card.id} to wallets: {e}")
+            synced = False
+            for attempt in range(2):  # 1 retry
+                try:
+                    results = wallet_service.sync_card_to_wallets(db, card)
+                    if results.get("google_wallet"):
+                        google_synced += 1
+                    if results.get("apple_wallet"):
+                        apple_synced += 1
+                    synced = True
+                    break
+                except Exception as e:
+                    if attempt == 0:
+                        logger.warning(
+                            f"Failed to sync card {card.id} (attempt 1/2), "
+                            f"retrying in 2s: {e}"
+                        )
+                        import time
+                        time.sleep(2)
+                    else:
+                        logger.error(
+                            f"Failed to sync card {card.id} after 2 attempts: {e}"
+                        )
+            if not synced:
+                failed_card_ids.append(card.id)
 
         logger.info(
             f"Wallet sync complete: {len(cards)} cards checked, "
-            f"{google_synced} Google, {apple_synced} Apple"
+            f"{google_synced} Google, {apple_synced} Apple, "
+            f"{len(failed_card_ids)} failed"
         )
 
         return {
@@ -87,6 +105,7 @@ def sync_wallet_passes() -> dict:
             "cards_checked": len(cards),
             "google_synced": google_synced,
             "apple_synced": apple_synced,
+            "failed_card_ids": failed_card_ids,
         }
 
     except Exception as e: