fix: strip /v2 suffix from broker base URL to prevent doubled path

The alpaca.url config file contains https://paper-api.alpaca.markets/v2
but the adapter code also prepends /v2/ to all paths, resulting in
/v2/v2/positions which returns 404. Now strips trailing /v2 or /v1
from the configured base URL since the adapter manages API versioning.

This was causing 1,017 consecutive broker sync failures.

services/adapters/broker_adapter.py

@@ -308,6 +308,11 @@ class AlpacaBrokerAdapter(BrokerDataAdapter):
         self.api_secret = api_secret
         if base_url:
             self.base_url = base_url.rstrip("/")
+            # Strip trailing /v2 or /v1 — the adapter adds API version prefixes itself
+            for suffix in ("/v2", "/v1"):
+                if self.base_url.endswith(suffix):
+                    self.base_url = self.base_url[: -len(suffix)]
+                    break
         elif mode == TradingMode.LIVE:
             self.base_url = self.LIVE_BASE_URL
         else: