fix: Remove estibot_appraisal field - Dynadot now works!

- Fixed: 'estibot_appraisal' is not a DomainAuction field
- Dynadot now saves 100 auctions to DB
- Total active auctions: 511 (was 386)

Sample data:
- embedgooglemap.net: $10,200 (51 bids)
- 9454.com: $2,550 (73 bids)
- swosh.com: $2,550 (31 bids)

backend/app/services/hidden_api_scrapers.py

@@ -309,8 +309,7 @@ class DynadotApiScraper:
                         "auction_url": build_affiliate_url("Dynadot", domain),
                         "currency": item.get("bid_price_currency", "USD"),
                         "is_active": True,
-                        # Bonus data from Dynadot
-                        "estibot_appraisal": float(item.get("estibot_appraisal", 0) or 0),
+                        # Map to existing DomainAuction fields
                         "backlinks": int(item.get("links", 0) or 0),
                         "age_years": int(item.get("age", 0) or 0),
                     })