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.Application/Interfaces/IAiCatalogPriceCheckService.cs

@@ -0,0 +1,16 @@
+using PowderCoating.Application.DTOs.AI;
+
+namespace PowderCoating.Application.Interfaces;
+
+public interface IAiCatalogPriceCheckService
+{
+    /// <summary>
+    /// Analyzes the provided catalog items against the shop's operating costs and returns
+    /// a verdict for each item. Items are batched into groups of 25 to stay within Claude's
+    /// context limits. Returns null results for any item that could not be analyzed.
+    /// </summary>
+    Task<List<CatalogItemPriceVerdict>> AnalyzeAsync(
+        List<CatalogItemForPriceCheck> items,
+        ShopOperatingCostSummary costs,
+        CancellationToken cancellationToken = default);
+}