New UploadSheet on the case detail page wraps react-dropzone + a
selector for doc_type. Files post to
POST /api/cases/{n}/documents/upload-tagged as multipart form-data;
the returned task_id is streamed via GET /api/progress/{task_id}
through the new lib/sse.ts EventSource wrapper.
Each upload row shows a per-file progress bar that transitions to
success/error on the terminal SSE payload. Closing the stream inside
the message handler avoids EventSource's auto-reconnect after EOF.
Phase 4 (task 86) is now complete end-to-end: create, upload, edit.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
