Phase G: Add Recurring Transactions (BackgroundService + CRUD UI)

- RecurringTemplate entity with Frequency/IntervalCount/NextFireDate/EndDate/MaxOccurrences/TemplateData JSON
- RecurringFrequency + RecurringTemplateType enums
- RecurringTransactionService BackgroundService: hourly check, creates Draft bills or immediate expenses, advances NextFireDate, auto-deactivates on limits
- RecurringTemplatesController: Index/Create/Edit/ToggleActive/Delete/GenerateNow (on-demand fire)
- Three views + external JS for type-toggle and dynamic bill line items
- Finance sidebar nav: Recurring Transactions
- Migration: AddRecurringTemplates

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

src/PowderCoating.Infrastructure/Repositories/UnitOfWork.cs

@@ -157,6 +157,9 @@ public class UnitOfWork : IUnitOfWork
     // Tax Rates
     private IRepository<TaxRate>? _taxRates;
 
+    // Recurring Transactions
+    private IRepository<RecurringTemplate>? _recurringTemplates;
+
     /// <summary>
     /// Initialises the unit of work with the scoped <paramref name="context"/>.
     /// The context is shared across all repositories created by this instance so that
@@ -560,6 +563,11 @@ public class UnitOfWork : IUnitOfWork
     public IRepository<TaxRate> TaxRates =>
         _taxRates ??= new Repository<TaxRate>(_context);
 
+    // Recurring Transactions
+    /// <summary>Repository for <see cref="RecurringTemplate"/> — saved recipes that auto-generate bills or expenses on a schedule.</summary>
+    public IRepository<RecurringTemplate> RecurringTemplates =>
+        _recurringTemplates ??= new Repository<RecurringTemplate>(_context);
+
     /// <summary>
     /// Flushes all pending changes in the EF Core change tracker to the database.
     /// Returns the number of state entries written.