feat(frontend): update API clients and Kanban components with enhanced UI

Ultraworked with [Sisyphus](https://github.com/code-yeongyu/oh-my-openagent)

Co-authored-by: Sisyphus <clio-agent@sisyphuslabs.ai>

frontend/src/api/document.ts

@@ -50,6 +50,25 @@ export interface UploadResponse {
   indexed_at?: string | null
 }
 
+export interface RAGSource {
+  id: string
+  title: string
+  file_type: string
+  similarity?: number
+  chunk_content?: string
+}
+
+export interface RAGChatRequest {
+  query: string
+  top_k?: number
+  mode?: 'hybrid' | 'semantic' | 'keyword'
+}
+
+export interface RAGChatResponse {
+  answer: string
+  sources: RAGSource[]
+}
+
 export const documentApi = {
   list(folderId?: string | null) {
     return api.get<Document[]>('/api/documents', {
@@ -93,4 +112,8 @@ export const documentApi = {
   getContent(id: string) {
     return api.get<string>(`/api/documents/${id}/content`)
   },
+
+  ragChat(payload: RAGChatRequest) {
+    return api.post<RAGChatResponse>('/api/documents/rag', payload)
+  },
 }