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/20260421103000_add_subcontractor_po_items.sql

@@ -0,0 +1,33 @@
+create table if not exists public.subcontractor_po_items (
+  id uuid default gen_random_uuid() primary key,
+  po_id uuid references public.subcontractor_payments(id) on delete cascade not null,
+  task_id uuid references public.tasks(id) on delete set null,
+  description text not null,
+  amount numeric(10,2) not null,
+  sort_order integer default 0 not null,
+  created_at timestamptz default now() not null
+);
+
+alter table public.subcontractor_po_items enable row level security;
+
+drop policy if exists "Team all subcontractor_po_items" on public.subcontractor_po_items;
+create policy "Team all subcontractor_po_items" on public.subcontractor_po_items
+  for all using (get_my_role() = 'team') with check (get_my_role() = 'team');
+
+drop policy if exists "External reads own subcontractor_po_items" on public.subcontractor_po_items;
+create policy "External reads own subcontractor_po_items" on public.subcontractor_po_items
+  for select using (
+    get_my_role() = 'external'
+    and po_id in (
+      select id from public.subcontractor_payments
+      where profile_id = auth.uid()
+    )
+  );
+
+insert into public.subcontractor_po_items (po_id, task_id, description, amount, sort_order)
+select id, null, description, amount, 0
+from public.subcontractor_payments sp
+where not exists (
+  select 1 from public.subcontractor_po_items item
+  where item.po_id = sp.id
+);