Add test/prod environments for databases

- Migration 010: test_* columns on databases table, environment column on request_logs
- DatabasePoolManager: dual-pool strategy (prod + test), getPool(id, env) with fallback
- All executors (SQL, Script, AQL): environment param threaded through execution paths
- dynamicApiController: X-Environment header detection, environment in logging
- databaseManagementController: CRUD for test credentials, testConnection with ?env=test
- Frontend: test env form in DatabaseModal, env toggle in EndpointEditor test panel

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

frontend/src/services/api.ts

@@ -86,8 +86,8 @@ export const dbManagementApi = {
   delete: (id: string) =>
     api.delete(`/db-management/${id}`),
 
-  test: (id: string) =>
-    api.get<{ success: boolean; message: string }>(`/db-management/${id}/test`),
+  test: (id: string, env?: 'prod' | 'test') =>
+    api.get<{ success: boolean; message: string }>(`/db-management/${id}/test${env === 'test' ? '?env=test' : ''}`),
 };
 
 // Endpoints API
@@ -120,6 +120,7 @@ export const endpointsApi = {
     aql_endpoint?: string;
     aql_body?: string;
     aql_query_params?: Record<string, string>;
+    environment?: 'prod' | 'test';
   }) =>
     api.post<QueryTestResult>('/endpoints/test', data),