fix: correct test suite failures for async price download

Fixed two test issues:
1. test_config_override.py: Updated hardcoded worktree path from config-override-system to async-price-download
2. test_dev_database.py: Added thread-local connection cleanup to prevent SQLite file locking issues

All tests now pass:
- Unit tests: 200 tests
- Integration tests: 47 tests (46 passed, 1 skipped)
- E2E tests: 3 tests
- Total: 250 tests collected

tests/integration/test_config_override.py

@@ -63,7 +63,7 @@ def test_config_override_models_only(test_configs):
         ],
         capture_output=True,
         text=True,
-        cwd="/home/bballou/AI-Trader/.worktrees/config-override-system"
+        cwd="/home/bballou/AI-Trader/.worktrees/async-price-download"
     )
 
     assert result.returncode == 0, f"Merge failed: {result.stderr}"
@@ -113,7 +113,7 @@ def test_config_validation_fails_gracefully(test_configs):
         ],
         capture_output=True,
         text=True,
-        cwd="/home/bballou/AI-Trader/.worktrees/config-override-system"
+        cwd="/home/bballou/AI-Trader/.worktrees/async-price-download"
     )
 
     assert result.returncode == 1