Site-wide rich search with keyword highlighting + header search box

- /Search: searches shifts, hiring openings, and applicants together via
  Postgres ILIKE (every term must match across role/city/facility/title/
  description/tags/person). Results grouped per type.
- Keyword highlighting (<mark>) extended to shift & job cards (was talent-only),
  so matches stand out everywhere.
- Persistent header search box (.nav-search) → /Search; big hero box on the
  page itself.

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

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

@@ -11,22 +11,23 @@
     if (Model.SalaryMin is null && Model.SalaryMax is null) salary = "توافقی";
     else if (Model.SalaryMin == Model.SalaryMax) salary = JalaliDate.Toman(Model.SalaryMin) + " ماهانه";
     else salary = $"از {JalaliDate.ToPersianDigits((Model.SalaryMin ?? 0).ToString("#,0"))} تا {JalaliDate.Toman(Model.SalaryMax)} ماهانه";
+    var q = ViewData["q"] as string;
 }
 <a class="card card-pad shift-card" asp-page="/Jobs/Details" asp-route-id="@Model.Id">
     <div class="row" style="justify-content: space-between;">
-        <span class="facility">@Model.Title</span>
+        <span class="facility">@JobsMedical.Web.Services.SearchHighlight.Mark(Model.Title, q)</span>
         <span class="badge badge-job">@empLabel</span>
     </div>
     <div class="row">
         @if (Model.Role is not null)
         {
-            <span class="badge badge-type">@Model.Role.Name</span>
+            <span class="badge badge-type">@JobsMedical.Web.Services.SearchHighlight.Mark(Model.Role.Name, q)</span>
         }
         @if (Model.GenderRequirement != Gender.Any)
         {
             <span class="badge badge-gender">@JalaliDate.GenderLabel(Model.GenderRequirement)</span>
         }
-        <span>🏥 @Model.Facility?.Name</span>
+        <span>🏥 @JobsMedical.Web.Services.SearchHighlight.Mark(Model.Facility?.Name, q)</span>
     </div>
     <div class="row">📍 @Model.Facility?.City?.Name@(Model.Facility?.District is not null ? "، " + Model.Facility.District.Name : "")</div>
     @if (Model.DistanceKm is double km)

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

@@ -117,6 +117,10 @@
                     <a asp-page="/Facilities/Index" class="@(path.StartsWith("/Facilities") ? "active" : null)">مراکز درمانی</a>
                     <a asp-page="/Calendar/Index" class="@(path.StartsWith("/Calendar") ? "active" : null)">تقویم هفتگی</a>
                 </nav>
+                <form class="nav-search" method="get" action="/Search" role="search">
+                    <input type="search" name="Q" placeholder="جستجو…" aria-label="جستجو" />
+                    <button type="submit" aria-label="جستجو">🔎</button>
+                </form>
                 <div class="header-actions">
                     <a class="btn btn-accent btn-sm cta-post" asp-page="/Employer/Index" data-tour="post">＋ ثبت آگهی</a>
                     @if (User.Identity?.IsAuthenticated == true)

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

@@ -7,16 +7,17 @@
         ShiftType.Night   => ("badge-night", "شب"),
         _                 => ("badge-oncall", "آنکال"),
     };
+    var q = ViewData["q"] as string;
 }
 <a class="card card-pad shift-card" asp-page="/Shifts/Details" asp-route-id="@Model.Id">
     <div class="row" style="justify-content: space-between;">
-        <span class="facility">@Model.Facility?.Name</span>
+        <span class="facility">@JobsMedical.Web.Services.SearchHighlight.Mark(Model.Facility?.Name, q)</span>
         <span class="badge @badgeClass">@typeLabel</span>
     </div>
     <div class="row">
         @if (Model.Role is not null)
         {
-            <span class="badge badge-type">@Model.Role.Name</span>
+            <span class="badge badge-type">@JobsMedical.Web.Services.SearchHighlight.Mark(Model.Role.Name, q)</span>
         }
         @if (Model.GenderRequirement != Gender.Any)
         {