Phase G: Add Budgeting and Year-End Close

Budgeting:
- Budget + BudgetLine entities with Jan–Dec monthly columns per GL account
- BudgetsController: Index, Create, Edit, SetDefault, Copy, Delete
- Copy action rolls a budget forward to a new fiscal year
- Budget vs. Actual report (BudgetVsActual): compares monthly budget amounts to
  real P&L by calling GetProfitAndLossAsync once per month; variance shown as
  favorable/unfavorable; year + budget selectors in header
- Views: Budgets/Index, Create, Edit with inline annual totals via budget-edit.js
- Nav link + report card on Landing

Year-End Close:
- YearEndClose entity records each closed year + JE reference for audit trail
- AccountsController.YearEndClose GET (history + form) + CloseYear POST
- Close zeroes all Revenue and Expense/COGS account balances into Retained Earnings
  via IAccountBalanceService and posts a supporting JE dated Dec 31
- Idempotency: rejects attempt to close an already-closed year
- Pre-close checklist in view to guide the workflow
- Nav link under Finance

Migration AddBudgetsAndYearEndClose applied

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

src/PowderCoating.Core/Interfaces/IUnitOfWork.cs

@@ -113,6 +113,13 @@ public interface IUnitOfWork : IDisposable
     IRepository<FixedAsset> FixedAssets { get; }
     IRepository<FixedAssetDepreciationEntry> FixedAssetDepreciationEntries { get; }
 
+    // Budgeting
+    IRepository<Budget> Budgets { get; }
+    IRepository<BudgetLine> BudgetLines { get; }
+
+    // Year-End Close
+    IRepository<YearEndClose> YearEndCloses { get; }
+
     // Notifications — typed repository for IgnoreQueryFilters-based history lookups
     INotificationLogRepository NotificationLogs { get; }
     IRepository<NotificationTemplate> NotificationTemplates { get; }