[UI] Fix navbar bell Razor leak, add Settings link, tidy desktop bar

Wrap the bell label in a span so the conditional parses as Razor code instead of leaking as literal text (Persian word char before the at-sign triggered email detection). Bell is icon-only on desktop, label shows in the mobile dropdown. Add a Settings link to admin actions so the demo-mode page is reachable from the navbar. Tighten desktop nav/action spacing.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

src/JobsMedical.Web/Pages/Shared/_Layout.cshtml

@@ -64,12 +64,13 @@
                         @if (User.IsInRole("Admin"))
                         {
                             <a class="nav-action" asp-page="/Admin/Overview">پنل مدیریت</a>
+                            <a class="nav-action" asp-page="/Admin/Settings">تنظیمات</a>
                         }
                         @if (User.IsInRole("FacilityAdmin"))
                         {
                             <a class="nav-action" asp-page="/Employer/Index">پنل کارفرما</a>
                         }
-                        <a class="nav-action bell-inline" asp-page="/Me/Notifications" title="اعلان‌ها">🔔 اعلان‌ها@if (unreadCount > 0) {<span class="bell-badge">@JalaliDate.ToPersianDigits(unreadCount > 99 ? "99+" : unreadCount.ToString())</span>}</a>
+                        <a class="nav-action bell-inline" asp-page="/Me/Notifications" title="اعلان‌ها"><span class="bell-ico">🔔</span><span class="bell-label">اعلان‌ها</span>@if (unreadCount > 0) {<span class="bell-badge">@JalaliDate.ToPersianDigits(unreadCount > 99 ? "99+" : unreadCount.ToString())</span>}</a>
                         <a class="nav-action" asp-page="/Me/Index">پنل کارجو</a>
                         <form method="post" asp-page="/Account/Logout" style="display:contents;">
                             <button type="submit" class="btn btn-outline btn-sm">خروج</button>