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/20260409120200_fix_submission_files_insert.sql

@@ -0,0 +1,28 @@
+drop policy if exists "Client inserts submission_files" on public.submission_files;
+drop policy if exists "External inserts submission_files" on public.submission_files;
+
+create policy "Client inserts submission_files" on public.submission_files
+  for insert with check (
+    get_my_role() = 'client'
+    and submission_id in (
+      select s.id
+      from public.submissions s
+      join public.tasks t on t.id = s.task_id
+      join public.projects p on p.id = t.project_id
+      where p.company_id = get_my_company_id()
+        and s.submitted_by = auth.uid()
+    )
+  );
+
+create policy "External inserts submission_files" on public.submission_files
+  for insert with check (
+    get_my_role() = 'external'
+    and submission_id in (
+      select s.id
+      from public.submissions s
+      join public.tasks t on t.id = s.task_id
+      join public.project_members pm on pm.project_id = t.project_id
+      where pm.profile_id = auth.uid()
+        and s.submitted_by = auth.uid()
+    )
+  );