fix: filter correlation matrix to tracked companies and make non-blocking

The correlation query was fetching 12K+ tickers from market_snapshots
instead of just the 50 tracked companies, causing OOM during startup.

- JOIN with companies table to filter to active tracked tickers only
- Move correlation computation to background task so engine starts trading immediately
- Add 30s timeout to prevent indefinite hangs

services/trading/engine.py

@@ -598,8 +598,9 @@ class TradingEngine:
             initial_capital, invested, available, reserve_balance, open_count,
         )
 
-        # Compute initial correlation matrix from market data
-        await self._compute_correlation_matrix()
+        # Compute initial correlation matrix from market data (non-blocking)
+        # Runs in background so the engine can start trading immediately
+        asyncio.create_task(self._compute_correlation_matrix(), name="correlation_matrix")
 
     async def _decision_loop(self) -> None:
         """Poll recommendations and evaluate them in a continuous loop.
@@ -1351,12 +1352,19 @@ class TradingEngine:
             return
 
         try:
-            rows = await self.pool.fetch(
-                "SELECT ticker, captured_at::date AS dt, (data->>'c')::float AS close "
-                "FROM market_snapshots "
-                "WHERE snapshot_type = 'bar' AND captured_at > NOW() - INTERVAL '30 days' "
-                "ORDER BY ticker, captured_at"
+            rows = await asyncio.wait_for(
+                self.pool.fetch(
+                    "SELECT ms.ticker, ms.captured_at::date AS dt, (ms.data->>'c')::float AS close "
+                    "FROM market_snapshots ms "
+                    "JOIN companies c ON c.ticker = ms.ticker AND c.active = TRUE "
+                    "WHERE ms.snapshot_type = 'bar' AND ms.captured_at > NOW() - INTERVAL '30 days' "
+                    "ORDER BY ms.ticker, ms.captured_at"
+                ),
+                timeout=30.0,
             )
+        except asyncio.TimeoutError:
+            logger.warning("Correlation matrix query timed out — skipping")
+            return
         except Exception:
             logger.debug("Could not query market_snapshots for correlation matrix")
             return