Feature: Google Drive file picker for multi-file import

Summary

Add a Google Drive file picker UI that allows users to select and import multiple documents at once.

Current State

• Google Drive OAuth is implemented in backend
• Single URL upload works via /documents/upload-url
• Manual URL pasting required for each file

Proposed Solution

1. Integrate Google Picker API in frontend
2. Add 'Import from Google Drive' button to document upload area
3. Allow multi-select in picker
4. Batch upload selected files using existing endpoint
5. Show progress for multi-file imports

Technical Notes

• Google Picker API: https://developers.google.com/drive/picker
• Need Picker API key in Google Cloud Console
• OAuth client ID already configured
• Backend endpoint ready: POST /documents/upload-url

Estimated Effort

4-8 hours

Labels

enhancement, frontend, google-drive