Fix flat-rate coat wizard UX, — literal, select caret overlap, and walkthrough modal sizing

- Flat-rate items now default coat type to Custom so Color Name field is immediately visible
- Catalog search blur copies typed text to Color Name when no catalog result was selected
- Item card shows 'No color specified' badge when coat has powder-to-order but no color name
- Color Name label marked required with '(shows on quote)' hint
- Coat name select min-width prevents text overlapping Bootstrap caret arrow
- Remove extra unbalanced </div> from renderSalesFields
- Fix literal &mdash; in quote simple-mode hint (textContent → innerHTML)
- Formula walkthrough modal fixed at 700px so all steps render at identical window size

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

src/PowderCoating.Web/Views/CompanySettings/Index.cshtml

@@ -2284,7 +2284,7 @@
 <!-- Custom Formula Walkthrough Modal -->
 <div class="modal fade" id="cfWalkthroughModal" tabindex="-1" aria-labelledby="cfWalkthroughLabel" aria-hidden="true">
     <div class="modal-dialog modal-lg modal-dialog-centered modal-dialog-scrollable">
-        <div class="modal-content">
+        <div class="modal-content" style="height:700px">
             <div class="modal-header border-0 pb-0">
                 <h5 class="modal-title" id="cfWalkthroughLabel">
                     <i class="bi bi-calculator text-info me-2"></i>Custom Formula Templates &mdash; How It Works