fix: resolve onboarding session not found warnings and frontend build OOM

- Use canonical Clerk user id (clerk_user_id) across all onboarding entrypoints to ensure consistent OnboardingSession.user_id lookup
- Fix API key persistence in api_key_manager.py to use correct APIKey model columns (session_id, provider, key)
- Increase Node heap for frontend build to 8GB and add build:nomap script to disable sourcemaps and reduce memory usage
- Update onboarding endpoints (endpoints_core.py, onboarding_control_service.py, step_management_service.py) to prefer clerk_user_id over id
- Fix frontend workflowStore.ts TypeScript error by returning WorkflowError instance
- Add website_automation_service.py for onboarding automation

frontend/package.json

@@ -37,7 +37,8 @@
   },
   "scripts": {
     "start": "react-scripts start",
-    "build": "react-scripts build",
+    "build": "node --max_old_space_size=8192 node_modules/react-scripts/scripts/build.js",
+    "build:nomap": "node --max_old_space_size=8192 -e \"process.env.GENERATE_SOURCEMAP='false'; require('./node_modules/react-scripts/scripts/build');\"",
     "test": "react-scripts test",
     "eject": "react-scripts eject",
     "analyze": "npm run build && npx source-map-explorer 'build/static/js/*.js' --html bundle-report.html",