fix: resolve remaining clippy warnings and improve workflow frontend

- Collapse nested if-let in user_service.rs search filter
- Suppress dead_code warning on ApiDoc struct
- Refactor server routing: nest all routes under /api/v1 prefix
- Simplify health check route path
- Improve workflow ProcessDesigner with edit mode and loading states
- Update workflow pages with enhanced UX
- Add Phase 2 implementation plan document

apps/web/src/pages/Workflow.tsx

@@ -9,7 +9,7 @@ export default function Workflow() {
   const [activeKey, setActiveKey] = useState('definitions');
 
   return (
-    <div style={{ padding: 24 }}>
+    <div>
       <Tabs
         activeKey={activeKey}
         onChange={setActiveKey}