fix(frontend): 修复合并审阅发现的构建与契约问题

恢复 Vue TypeScript 生产构建，补齐可运行页面壳子，并修复文件树与 SSE 状态问题。

按 FastAPI Wire Contract 统一 Service DTO 映射，同时补充前端开发说明和问题修复复盘。

frontend/src/services/indexService.ts

@@ -1,25 +1,29 @@
 import apiClient from './apiClient'
-import type { IndexStatus } from '@/contracts'
+import type { ApiIndexJob, ApiIndexStatus, IndexStatus } from '@/contracts'
 
-export async function getIndexStatus(): Promise<IndexStatus> {
-  try {
-    return await apiClient.get('/api/index/status')
-  } catch {
-    return mockIndexStatus
+function toIndexStatus(status: ApiIndexStatus): IndexStatus {
+  return {
+    status: status.status === 'idle' ? 'idle' : status.status === 'failed' ? 'error' : 'indexing',
+    pending_jobs: status.pending_jobs,
+    total_notes: 0,
+    total_blocks: 0,
+    fts_enabled: true,
+    vector_enabled: true,
+    last_indexed_at: status.last_completed_at ?? undefined,
+    error: status.error_message ?? undefined,
   }
 }
 
-export async function rebuildIndex(scope: 'full' | 'fts' | 'vector' = 'full'): Promise<{ job_id: string }> {
-  return apiClient.post('/api/index/rebuild', { scope })
+export async function getIndexStatus(): Promise<IndexStatus> {
+  return toIndexStatus(await apiClient.get<ApiIndexStatus>('/api/index/status'))
 }
 
-export async function getIndexJob(jobId: string): Promise<{
-  job_id: string
-  status: 'queued' | 'running' | 'completed' | 'failed'
-  progress: number
-  total: number
-  error?: string
-}> {
+export async function rebuildIndex(scope: 'full' | 'fts' | 'vector' = 'full'): Promise<ApiIndexJob> {
+  const apiScope = scope === 'full' ? 'all' : scope === 'fts' ? 'notes' : 'vectors'
+  return apiClient.post<ApiIndexJob>('/api/index/rebuild', { scope: apiScope })
+}
+
+export async function getIndexJob(jobId: string): Promise<ApiIndexJob> {
   return apiClient.get(`/api/index/jobs/${jobId}`)
 }