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>

wwwroot/js/catalog-price-check.js

@@ -0,0 +1,12 @@
+(function () {
+    'use strict';
+
+    var form = document.getElementById('runForm');
+    var btn = document.getElementById('runBtn');
+    if (!form || !btn) return;
+
+    form.addEventListener('submit', function () {
+        btn.disabled = true;
+        btn.innerHTML = '<span class="spinner-border spinner-border-sm me-2"></span>Analyzing with AI…';
+    });
+}());