Fix script execution logs being lost

- Add ScriptExecutionError class that preserves captured logs/queries
- IsolatedScriptExecutor: throw ScriptExecutionError with accumulated
  logs instead of plain Error on script failure
- ScriptExecutor (Python): same fix for Python execution errors
- testEndpoint: return captured logs/queries on script errors
- dynamicApiController: correctly extract scriptResult.result instead
  of stuffing entire IsolatedExecutionResult into rows; include logs
  in detailed_response output

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

backend/src/controllers/endpointController.ts

@@ -2,7 +2,7 @@ import { Response } from 'express';
 import { AuthRequest } from '../middleware/auth';
 import { mainPool } from '../config/database';
 import { v4 as uuidv4 } from 'uuid';
-import { ExportedEndpoint, ExportedScriptQuery } from '../types';
+import { ExportedEndpoint, ExportedScriptQuery, ScriptExecutionError } from '../types';
 import { encryptEndpointData, decryptEndpointData } from '../services/endpointCrypto';
 
 export const getEndpoints = async (req: AuthRequest, res: Response) => {
@@ -388,13 +388,14 @@ export const testEndpoint = async (req: AuthRequest, res: Response) => {
       return res.status(400).json({ error: 'Invalid execution_type' });
     }
   } catch (error: any) {
+    const isScriptError = error instanceof ScriptExecutionError;
     res.status(400).json({
       success: false,
       error: error.message,
       detail: error.detail || undefined,
       hint: error.hint || undefined,
-      logs: [],
-      queries: [],
+      logs: isScriptError ? error.logs : [],
+      queries: isScriptError ? error.queries : [],
     });
   }
 };