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/Data/ApplicationDbContext.cs

@@ -335,6 +335,9 @@ public class ApplicationDbContext : IdentityDbContext<ApplicationUser>, IDataPro
     /// <summary>Named tax rates used to pre-fill invoice tax percent by jurisdiction; tenant-filtered with soft delete.</summary>
     public DbSet<TaxRate> TaxRates { get; set; }
 
+    /// <summary>Recurring transaction templates that auto-generate bills or expenses on a schedule; tenant-filtered with soft delete.</summary>
+    public DbSet<RecurringTemplate> RecurringTemplates { get; set; }
+
     /// <summary>Credit notes received from vendors (returned goods, pricing disputes); tenant-filtered with soft delete.</summary>
     public DbSet<VendorCredit> VendorCredits { get; set; }
     /// <summary>Expense-reversal line items on a vendor credit; soft-delete only.</summary>
@@ -645,6 +648,10 @@ public class ApplicationDbContext : IdentityDbContext<ApplicationUser>, IDataPro
         modelBuilder.Entity<TaxRate>().HasQueryFilter(e =>
             !e.IsDeleted && (IsPlatformAdmin || e.CompanyId == CurrentCompanyId));
 
+        // Recurring Templates: tenant-filtered
+        modelBuilder.Entity<RecurringTemplate>().HasQueryFilter(e =>
+            !e.IsDeleted && (IsPlatformAdmin || e.CompanyId == CurrentCompanyId));
+
         // Vendor Credits: tenant-filtered; child rows soft-delete only
         modelBuilder.Entity<VendorCredit>().HasQueryFilter(e =>
             !e.IsDeleted && (IsPlatformAdmin || e.CompanyId == CurrentCompanyId));