fix: Improved duplicate prevention in cast iron scanner

- Better link normalization and checking
- Skip items already in seen_links with logging
- Clean up state file to last 500 items
- Always mark items as seen (deal or not)
- Added logging for skipped duplicates

Also: eBay scraping temporarily blocked/changed - investigating

agents/junior-ae/state/jae-v4-state.json

@@ -1,5 +1,5 @@
 {
-  "last_check": "2026-04-10T10:09:06.314350",
+  "last_check": "2026-04-10T13:10:34.858296",
   "processed": 0,
   "upgraded": 0,
   "processed_ids": [