Fix file sharing load speed and move error; misc updates

- Remove recursive directory size calculations (single Seafile API call per list)
- Remove 'Used in this location' usage display
- Fix move using v2 per-type endpoints instead of broken batch endpoint
- Send entry type from frontend for correct move routing

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

supabase/migrations/20260409110000_add_fourge_files_bucket.sql

@@ -0,0 +1,17 @@
+insert into storage.buckets (id, name, public)
+select 'fourge-files', 'fourge-files', false
+where not exists (
+  select 1 from storage.buckets where id = 'fourge-files'
+);
+
+create policy "Team reads fourge files storage" on storage.objects
+  for select to authenticated
+  using (bucket_id = 'fourge-files' and get_my_role() = 'team');
+
+create policy "Team inserts fourge files storage" on storage.objects
+  for insert to authenticated
+  with check (bucket_id = 'fourge-files' and get_my_role() = 'team');
+
+create policy "Team deletes fourge files storage" on storage.objects
+  for delete to authenticated
+  using (bucket_id = 'fourge-files' and get_my_role() = 'team');