feat: Cast Iron Scout agent prototype

- Created autonomous cast iron deal scanner
- Scans eBay RSS feeds hourly for cast iron cookware
- Calculates FMV based on brand, type, size
- Sends Telegram alerts for deals ≥50% below FMV
- Identifies Griswold, Wagner, Wapak, Birmingham, Lodge, Victor
- Tracks seen items to avoid duplicate alerts
- Valuation engine with size multipliers
- Configurable preferences in config.json

Known issue: eBay RSS unreliable - next iteration will use proper scraping

agents/cast-iron-scout/config.json

@@ -0,0 +1,44 @@
+{
+  "scan_interval_minutes": 30,
+  "min_discount_percent": 50,
+  "max_distance_miles": 500,
+  "preferred_brands": [
+    "griswold",
+    "wagner",
+    "wapak",
+    "birmingham",
+    "lodge",
+    "victor",
+    "hollowware"
+  ],
+  "item_types": [
+    "skillet",
+    "griddle",
+    "dutch oven",
+    "pot",
+    "pan",
+    "grill pan",
+    "waffle iron",
+    "mold"
+  ],
+  "condition_keywords": [
+    "rust",
+    "restoration",
+    "as-is",
+    "vintage",
+    "antique",
+    "estate",
+    "garage sale",
+    "dirty",
+    "needs work"
+  ],
+  "exclude_keywords": [
+    "new",
+    "reproduction",
+    "replica",
+    "modern",
+    "calphalon",
+    "le creuset"
+  ],
+  "telegram_target": "telegram:8269921691"
+}