Budget Workbook: replace Budget Management with a YTD-actuals workbook

/dashboard/budget-management now renders a Budget Workbook that pulls YTD
actuals (from the accounting GL, through a chosen month), derives a monthly
average (YTD/N), takes a per-line inflation %, and projects an annual budget
(avg x 12 x (1+infl)). Footer rolls up annual budget / 12 / # units = per-unit
monthly assessment. Income + expense sections; all imported fields editable.

- Standalone saved worksheet (accounting.budget_workbooks/_lines, RLS like accounts)
- "Push to Budget" writes projected/12 into accounting.budgets + budget_entries
- Uses accounting.accounts (synced with the Accounting dashboard COA) and paginates
  the GL fetch (1000-row cap). Nav relabeled Budget Management -> Budget Workbook.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

supabase/migrations/20260609170000_budget_workbook.sql

@@ -0,0 +1,41 @@
+-- Budget Workbook: standalone worksheet state (chosen month + per-line inflation %
+-- and overrides) for the Budget Workbook page. Computed values come from the GL at
+-- runtime; only the user's edits are persisted here. Company-scoped, RLS mirrors
+-- accounting.accounts (accounting staff OR company member).
+
+create table if not exists accounting.budget_workbooks (
+  id uuid primary key default gen_random_uuid(),
+  company_id uuid not null references accounting.companies(id) on delete cascade,
+  fiscal_year int not null,
+  through_month int not null default 1,
+  created_at timestamptz not null default now(),
+  updated_at timestamptz not null default now(),
+  unique (company_id, fiscal_year)
+);
+
+create table if not exists accounting.budget_workbook_lines (
+  id uuid primary key default gen_random_uuid(),
+  workbook_id uuid not null references accounting.budget_workbooks(id) on delete cascade,
+  account_id uuid not null references accounting.accounts(id) on delete cascade,
+  ytd_override numeric,
+  inflation_pct numeric,
+  projected_override numeric,
+  unique (workbook_id, account_id)
+);
+
+alter table accounting.budget_workbooks enable row level security;
+alter table accounting.budget_workbook_lines enable row level security;
+
+create policy "wb staff" on accounting.budget_workbooks for all to authenticated
+  using (accounting.is_accounting_staff()) with check (accounting.is_accounting_staff());
+create policy "wb members" on accounting.budget_workbooks for all to authenticated
+  using (accounting.is_company_member(company_id, auth.uid())) with check (accounting.is_company_member(company_id, auth.uid()));
+
+create policy "wbl staff" on accounting.budget_workbook_lines for all to authenticated
+  using (accounting.is_accounting_staff()) with check (accounting.is_accounting_staff());
+create policy "wbl members" on accounting.budget_workbook_lines for all to authenticated
+  using (exists (select 1 from accounting.budget_workbooks w where w.id = workbook_id and accounting.is_company_member(w.company_id, auth.uid())))
+  with check (exists (select 1 from accounting.budget_workbooks w where w.id = workbook_id and accounting.is_company_member(w.company_id, auth.uid())));
+
+grant select, insert, update, delete on accounting.budget_workbooks to authenticated;
+grant select, insert, update, delete on accounting.budget_workbook_lines to authenticated;