Improve request logging and make health check lightweight

- Log slow requests (>1s) at WARNING level with slow=true flag
- Log request timeouts at WARNING level in TimeoutMiddleware
- Replace heavy GetStatsContext with lightweight Ping in health check
- Add Ping method to database interface (SELECT 1)

internal/routewatch/app_integration_test.go

@@ -420,6 +420,11 @@ func (m *mockStore) Checkpoint(ctx context.Context) error {
 	return nil
 }
 
+// Ping mock implementation
+func (m *mockStore) Ping(ctx context.Context) error {
+	return nil
+}
+
 func TestRouteWatchLiveFeed(t *testing.T) {
 
 	// Create mock database