Design consistency audit fixes: alerts, cards, dark mode, utilities

Alert sweep (113 alerts, 79 files):
  All persistent static banners now carry alert-permanent so the
  layout's 5-second auto-dismiss cannot swallow guidance, warnings,
  or validation errors. Transient dismissible toasts left untouched.

CSS fixes (site.css):
  .card.shadow-sm      — strips rogue border from ~40 drifted cards
  .card-header.bg-white — rebinds to var(--bs-body-bg) so card
                          headers follow dark/light theme correctly
  Typography utilities  — .text-2xs (.68rem), .text-xs (.73rem)
  Token color classes   — .text-ember, .text-ok, .text-bad,
                          .text-warn, .text-cool, .bg-paper-2
  Layout utilities      — .mw-xs/sm/md/lg replace inline max-width
  Comment              — documents text-ember vs text-primary intent

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

src/PowderCoating.Web/Views/Inventory/Delete.cshtml

@@ -1,4 +1,4 @@
-@model PowderCoating.Application.DTOs.Inventory.InventoryItemDto
+@model PowderCoating.Application.DTOs.Inventory.InventoryItemDto
 
 @{
     ViewData["Title"] = "Delete Inventory Item";
@@ -14,7 +14,7 @@
         </div>
 
         <!-- Warning Banner -->
-        <div class="alert alert-danger d-flex align-items-start mb-4">
+        <div class="alert alert-danger alert-permanent d-flex align-items-start mb-4">
             <i class="bi bi-exclamation-triangle-fill me-3" style="font-size: 1.5rem;"></i>
             <div>
                 <h5 class="alert-heading mb-2">Are you sure you want to delete this inventory item?</h5>
@@ -143,7 +143,7 @@
 
                 @if (Model.QuantityOnHand > 0)
                 {
-                    <div class="alert alert-warning d-flex align-items-center">
+                    <div class="alert alert-warning alert-permanent d-flex align-items-center">
                         <i class="bi bi-exclamation-circle me-2"></i>
                         <div>
                             <strong>Warning:</strong> This item still has @Model.QuantityOnHand.ToString("N2") @Model.UnitOfMeasure in stock (value: @((Model.QuantityOnHand * Model.UnitCost).ToString("C"))). Consider transferring or adjusting inventory before deletion.