Add AI Catalog Price Check feature

Claude reviews every active catalog item against the shop's own operating costs
and returns a per-item verdict (below-cost / thin-margin / high / ok) with a
suggested price range, cost floor, and assumptions.

- New entity: CatalogPriceCheckReport (JSON blob, archived per company)
- New service: IAiCatalogPriceCheckService / AiCatalogPriceCheckService
  batches items 25 at a time to stay within model context limits
- Two new controller actions: GET AiPriceCheck (view report) + POST RunAiPriceCheck
- AiPriceCheck view: summary cards (counts by verdict), color-coded item cards
  with Edit Price link, assumptions detail, and loading spinner on submit
- AI Price Check button added to catalog Index header
- Migration AddCatalogPriceCheckReport applied

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

src/PowderCoating.Infrastructure/Data/ApplicationDbContext.cs

@@ -260,6 +260,8 @@ public class ApplicationDbContext : IdentityDbContext<ApplicationUser>
     public DbSet<CatalogCategory> CatalogCategories { get; set; }
     /// <summary>Pre-priced service catalog items that can be added to quotes/jobs; tenant-filtered with soft delete.</summary>
     public DbSet<CatalogItem> CatalogItems { get; set; }
+    /// <summary>Most-recent AI price-check report per company; tenant-filtered with soft delete.</summary>
+    public DbSet<CatalogPriceCheckReport> CatalogPriceCheckReports { get; set; }
 
     // Notifications
     /// <summary>Log of all outbound notifications (email, SMS, in-app) for audit and retry; tenant-filtered with soft delete.</summary>
@@ -508,6 +510,8 @@ public class ApplicationDbContext : IdentityDbContext<ApplicationUser>
             !e.IsDeleted && (IsPlatformAdmin || e.CompanyId == CurrentCompanyId));
         modelBuilder.Entity<CatalogItem>().HasQueryFilter(e =>
             !e.IsDeleted && (IsPlatformAdmin || e.CompanyId == CurrentCompanyId));
+        modelBuilder.Entity<CatalogPriceCheckReport>().HasQueryFilter(e =>
+            !e.IsDeleted && (IsPlatformAdmin || e.CompanyId == CurrentCompanyId));
 
         modelBuilder.Entity<Appointment>().HasQueryFilter(e =>
             !e.IsDeleted && (IsPlatformAdmin || e.CompanyId == CurrentCompanyId));