Feature: Royal Mail tracking integration (hybrid approach)

Add ability to sync shipment tracking data from Royal Mail API:

- Create Royal Mail API service (src/lib/royalmail.ts) to fetch tracking status
- Add sync-tracking endpoint to pull latest status from Royal Mail
- Create SyncRoyalMailButton component for admin panel
- Add 'Sync from Royal Mail' button on order detail page
- Auto-update order status based on Royal Mail tracking status

Admin workflow:
1. Create shipping label in Royal Mail Click & Drop
2. Copy tracking number into tracking form
3. Click 'Sync from Royal Mail' to fetch and update status
4. System maps Royal Mail status to our order status (SHIPPED, DELIVERED, etc)

Uses Royal Mail's public tracking API - no special credentials required.
Supports manual label creation workflow (hybrid approach).

.claude/settings.local.json

@@ -76,7 +76,8 @@
       "Bash(git commit -m 'Fix: Ensure cart is completely cleared after payment success *)",
       "Bash(git commit -m 'Fix: Update order status to PAID on checkout success page *)",
       "Bash(git commit -m 'Improve: Cart clearing on success page with better state management *)",
-      "Bash(git commit -m 'Feature: Add order tracking and shipping status updates *)"
+      "Bash(git commit -m 'Feature: Add order tracking and shipping status updates *)",
+      "Bash(git commit -m 'Feature: Royal Mail tracking integration \\(hybrid approach\\) *)"
     ]
   }
 }