Fix bugs: monthly actuals month filter, unit assessments, project funding logic, UI cleanup

- Fix monthly actuals showing same data for all months (SQL JOIN excluded
  month filter from SUM — added je.id IS NOT NULL guard)
- Fix units displaying $0 assessment by reading from assessment group
  instead of stale unit field; add special assessment column
- Replace proportional project funding with priority-based sequential
  allocation — near-term items get fully funded first; add is_funding_locked
  flag so users can manually lock a project's fund balance
- Remove post-creation opening balance UI (keep only initial balance on
  account creation); remove redundant Fund filter dropdown from Accounts

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

backend/src/modules/monthly-actuals/monthly-actuals.service.ts

@@ -28,8 +28,10 @@ export class MonthlyActualsService {
         a.fund_type,
         COALESCE(b.${budgetCol}, 0) as budget_amount,
         COALESCE(SUM(
-          CASE WHEN a.account_type IN ('expense', 'asset') THEN jel.debit - jel.credit
-               ELSE jel.credit - jel.debit END
+          CASE WHEN je.id IS NOT NULL THEN
+            CASE WHEN a.account_type IN ('expense', 'asset') THEN jel.debit - jel.credit
+                 ELSE jel.credit - jel.debit END
+          END
         ), 0) as actual_amount
       FROM accounts a
       LEFT JOIN budgets b ON b.account_id = a.id AND b.fiscal_year = $1