feat: Add directory tree tab to session files

web/src/api/client.ts

@@ -2,6 +2,7 @@ import type {
     AttachmentMetadata,
     AuthResponse,
     DeleteUploadResponse,
+    ListDirectoryResponse,
     FileReadResponse,
     FileSearchResponse,
     GitCommandResponse,
@@ -239,6 +240,18 @@ export class ApiClient {
         return await this.request<FileReadResponse>(`/api/sessions/${encodeURIComponent(sessionId)}/file?${params.toString()}`)
     }
 
+    async listSessionDirectory(sessionId: string, path?: string): Promise<ListDirectoryResponse> {
+        const params = new URLSearchParams()
+        if (path) {
+            params.set('path', path)
+        }
+
+        const qs = params.toString()
+        return await this.request<ListDirectoryResponse>(
+            `/api/sessions/${encodeURIComponent(sessionId)}/directory${qs ? `?${qs}` : ''}`
+        )
+    }
+
     async uploadFile(sessionId: string, filename: string, content: string, mimeType: string): Promise<UploadFileResponse> {
         return await this.request<UploadFileResponse>(`/api/sessions/${encodeURIComponent(sessionId)}/upload`, {
             method: 'POST',