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/20260421120000_require_nonblank_project_names.sql

@@ -0,0 +1,10 @@
+update public.projects
+set name = 'Untitled Project ' || left(id::text, 8)
+where length(trim(coalesce(name, ''))) = 0;
+
+alter table public.projects
+  drop constraint if exists projects_name_not_blank;
+
+alter table public.projects
+  add constraint projects_name_not_blank
+  check (length(trim(name)) > 0);