Generate navigation, navigation search (#18096)

### Summary
2 API

POST /api/v1/datasets/{dataset_id}/navigation

GET
/api/v1/datasets/{dataset_id}/navigation/search?q={query}&mode={mode}&top_k={topk}


2 cli

uv run --no-sync python3 admin/client/ragflow_cli.py -h 127.0.0.1 -p
9380 -t user

ragflow> GENERATE NAVIGATION OF DATASET 'frames tree';

ragflow> NAVIGATION SEARCH 'Christie introduced blockchain-based digital
passports' IN DATASET 'frames tree' MODE 'all' topk 20;

(mode: chunk, nav_cluster, nav_doc, navigation_tree, all)

web/src/interfaces/database/dataset-nav.ts

@@ -3,8 +3,11 @@ export interface DatasetNavNode {
   description: string;
   doc_count: number;
   type: string;
-  doc_id?: string; // only returned by the children endpoint
+  doc_id?: string;
   has_children: boolean;
+  keywords?: string[];
+  entities?: string[];
+  graph_content?: string;
 }
 
 export interface DatasetNavList {