feat(data): add Polymarket prediction markets as a keyless vendor

Surface live, market-implied probabilities for forward-looking events (Fed
decisions, recession, elections, geopolitics, crypto) to the news analyst via a
new get_prediction_markets tool and a prediction_markets vendor category. Backed
by Polymarket's public Gamma API (no key). Results are filtered to open,
forward-looking markets (closed and past-dated events excluded), ranked by
traded volume, and rendered with implied probability, volume, resolution date,
and the recent move. External errors degrade to a clear unavailable message
rather than interrupting the analyst.

tradingagents/dataflows/interface.py

@@ -25,6 +25,7 @@ from .alpha_vantage import (
 )
 from .alpha_vantage_common import AlphaVantageRateLimitError
 from .fred import get_macro_data as get_fred_macro_data
+from .polymarket import get_prediction_markets as get_polymarket_prediction_markets
 from .symbol_utils import NoMarketDataError
 
 # Configuration and routing logic
@@ -68,12 +69,19 @@ TOOLS_CATEGORIES = {
         "tools": [
             "get_macro_indicators",
         ]
+    },
+    "prediction_markets": {
+        "description": "Market-implied probabilities for forward-looking events",
+        "tools": [
+            "get_prediction_markets",
+        ]
     }
 }
 
 VENDOR_LIST = [
     "yfinance",
     "fred",
+    "polymarket",
     "alpha_vantage",
 ]
 
@@ -123,6 +131,10 @@ VENDOR_METHODS = {
     "get_macro_indicators": {
         "fred": get_fred_macro_data,
     },
+    # prediction_markets
+    "get_prediction_markets": {
+        "polymarket": get_polymarket_prediction_markets,
+    },
 }
 
 def get_category_for_method(method: str) -> str: