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/Shared/_Layout.cshtml

@@ -1503,10 +1503,10 @@
                         aria-label="Toggle sidebar">
                     <i class="bi bi-list" style="font-size: 1.5rem;"></i>
                 </button>
-                <div class="d-flex align-items-center gap-2">
+                <div class="d-flex align-items-center gap-2" style="min-width:0;overflow:hidden;">
                     @if (ViewData["PageIcon"] != null)
                     {
-                        <i class="bi @ViewData["PageIcon"]" style="font-size:1.25rem;color:var(--bs-secondary-color);"></i>
+                        <i class="bi @ViewData["PageIcon"]" style="font-size:1.25rem;color:var(--bs-secondary-color);flex-shrink:0;"></i>
                     }
                     <h1 class="page-title mb-0">@ViewData["Title"]</h1>
                     @if (ViewData["PageHelpContent"] != null)
@@ -2287,7 +2287,7 @@
                     <p class="text-muted mb-0" id="globalConfirmMessage"></p>
                 </div>
                 <div class="modal-footer border-0 justify-content-center gap-2 pb-4">
-                    <button type="button" class="btn btn-secondary px-4" id="globalConfirmCancel">Cancel</button>
+                    <button type="button" class="btn btn-outline-secondary px-4" id="globalConfirmCancel">Cancel</button>
                     <button type="button" class="btn btn-danger px-4" id="globalConfirmOk">Confirm</button>
                 </div>
             </div>