Upload pipeline: staging, MD5 auto-match, IQDB, three-column board

Backend:
- TempUpload model: staged files (pending / visual_match / completed /
  error) with resolution, e621 payload, custom metadata and IQDB data
- Files land in a temp folder and only move into the watched library
  folder once resolved; duplicates resolve immediately without a copy
- Endpoints: stage (multipart), list, retrieve, temp file, IQDB save,
  resolve (link to post or custom metadata), discard/dismiss
- cleanup_temp_uploads command for old staged files
- Replaces the old direct-to-library upload endpoint

Frontend:
- Upload page is now a three-column board (Pending & Unmatched /
  Visual Similarity Detected / Auto-uploaded & Indexed)
- After upload: MD5s are batch-checked against e621 and matches
  auto-complete with full post metadata; remaining files run through
  IQDB and move to the similarity column when candidates exist
- Metadata modal with IQDB candidates, post-ID linking and custom
  tags/rating/notes; discard and dismiss actions
- e621 client gains fetchPostsByMd5 and iqdbSearch helpers

Roadmap updated with the completed upload items.

backend/apps/library/views.py

@@ -8,7 +8,6 @@ from django.http import Http404
 from django.shortcuts import get_object_or_404
 from rest_framework import mixins, status, viewsets
 from rest_framework.decorators import action
-from rest_framework.parsers import FormParser, MultiPartParser
 from rest_framework.permissions import AllowAny, IsAuthenticatedOrReadOnly
 from rest_framework.response import Response
 from rest_framework.views import APIView
@@ -165,55 +164,6 @@ class MediaItemViewSet(
         )
 
 
-class UploadView(APIView):
-    permission_classes = [CanUpload]
-    parser_classes = [MultiPartParser, FormParser]
-
-    def post(self, request):
-        upload = request.FILES.get("file")
-        if upload is None:
-            return Response(
-                {"detail": "A file is required."}, status=status.HTTP_400_BAD_REQUEST
-            )
-        folder = Path(settings.WATCHED_FOLDER)
-        destination = services.unique_destination(folder, upload.name)
-        with open(destination, "wb") as output:
-            for chunk in upload.chunks():
-                output.write(chunk)
-        try:
-            item, created_item, _ = services.index_file(destination, folder)
-        except Exception as exc:  # noqa: BLE001 - report indexing failures
-            destination.unlink(missing_ok=True)
-            return Response(
-                {"detail": f"Could not index upload: {exc}"},
-                status=status.HTTP_400_BAD_REQUEST,
-            )
-
-        update_fields = []
-        if created_item and item.uploaded_by_id is None:
-            item.uploaded_by = request.user
-            update_fields.append("uploaded_by")
-        rating = request.data.get("rating") or ""
-        if rating in {"s", "q", "e"} and item.rating != rating:
-            item.rating = rating
-            update_fields.append("rating")
-        tags = services.parse_tags(request.data.get("tags"))
-        if tags is not None:
-            item.tags = tags
-            update_fields.append("tags")
-        notes = request.data.get("notes")
-        if notes is not None:
-            item.notes = str(notes)
-            update_fields.append("notes")
-        if update_fields:
-            item.save(update_fields=update_fields + ["updated_at"])
-
-        return Response(
-            MediaItemSerializer(item, context={"request": request}).data,
-            status=status.HTTP_201_CREATED,
-        )
-
-
 class DownloadToLibraryView(APIView):
     """Fetch an e621 file into the watched folder and index it."""