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/TwoFactorSetup/Setup.cshtml

@@ -1,4 +1,4 @@
-@{
+@{
     ViewData["Title"] = "Set Up Two-Factor Authentication";
 }
 
@@ -15,7 +15,7 @@
         <div class="card-body">
             <ol class="mb-0 ps-3">
                 <li class="mb-3">
-                    <strong>Install an authenticator app</strong> on your phone if you haven't already —
+                    <strong>Install an authenticator app</strong> on your phone if you haven't already —
                     <em>Google Authenticator</em>, <em>Microsoft Authenticator</em>, or <em>Authy</em> all work.
                 </li>
                 <li class="mb-3">
@@ -26,7 +26,7 @@
                              class="border rounded p-1"
                              style="width:200px;height:200px" />
                     </div>
-                    <div class="alert alert-light py-2 small">
+                    <div class="alert alert-light alert-permanent py-2 small">
                         <strong>Manual entry key:</strong><br>
                         <code class="user-select-all">@ViewBag.SharedKey</code>
                     </div>