feat(iframe): add iframe bridge for ragflow integration

- Implement Penpal-based iframe communication bridge between host and child apps
- Add route handling for ragflow integration with '/route-ragflow' prefix
- Update navigation hooks to support embedded mode via iframe bridge
- Configure build and dependencies for new iframe-bridge package
- Adjust nginx config for proper SPA routing in subpath deployments

ragflow_web/.umirc.ts

@@ -11,6 +11,7 @@ export default defineConfig({
   outputPath: 'dist',
   alias: { '@parent': path.resolve(__dirname, '../') },
   npmClient: 'pnpm',
+  mfsu: false,
   base: RAGFLOW_BASE,
   routes,
   publicPath: RAGFLOW_BASE,