Button consistency sweep + mobile responsiveness patches

- Standardize modal dismiss/cancel buttons to btn-outline-secondary across 70+ views
- Remove btn-sm from page-level Create and Back buttons (Index + Detail pages)
- Fix Edit buttons on Details pages: btn-secondary -> btn-warning
- Fix form Cancel/Back links: btn-secondary -> btn-outline-secondary
- Add 10 CSS patches to site.css for mobile/tablet responsiveness:
  top-navbar overflow prevention, page-header flex-wrap at 575px,
  table action button min-height override, notification dropdown width cap,
  tablet content padding

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

src/PowderCoating.Web/Views/Budgets/Create.cshtml

@@ -8,7 +8,7 @@
 }
 
 <div class="mb-4">
-    <a asp-action="Index" class="btn btn-outline-secondary btn-sm">
+    <a asp-action="Index" class="btn btn-outline-secondary">
         <i class="bi bi-arrow-left me-1"></i>Back to Budgets
     </a>
 </div>
@@ -48,7 +48,7 @@
         <div class="card-header bg-white border-0 py-3 d-flex justify-content-between align-items-center">
             <h5 class="mb-0 fw-semibold"><i class="bi bi-table me-2 text-primary"></i>Monthly Amounts by Account</h5>
             <div class="d-flex gap-2">
-                <button type="button" class="btn btn-outline-secondary btn-sm" id="fillEvenlyBtn">
+                <button type="button" class="btn btn-sm btn-outline-secondary" id="fillEvenlyBtn">
                     <i class="bi bi-distribute-horizontal me-1"></i>Spread Annual Evenly
                 </button>
             </div>