Search: Elasticsearch-style highlighted match snippets (results + typeahead)

- SearchHighlight.Snippet: extracts a ±70-char window around the first
  matching term and marks it (with ellipses) — the ES "highlight" fragment.
- Result cards (shift/job/talent) now show that snippet from the matched
  description/tags when a query is present, so you SEE where the term hit
  (e.g. «…دارای مدرک <mark>mmt</mark>…») instead of just the role.
- Typeahead suggestions gain a highlighted "sub" line (talent→tags,
  shift→city·specialty, job→facility·city) so matches show in the dropdown too.

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

src/JobsMedical.Web/Services/SearchHighlight.cs

@@ -24,4 +24,33 @@ public static class SearchHighlight
         var marked = Regex.Replace(encoded, pattern, m => $"<mark>{m.Value}</mark>", RegexOptions.IgnoreCase);
         return new HtmlString(marked);
     }
+
+    /// <summary>
+    /// Elasticsearch-style highlight fragment: finds the first matching term in <paramref name="text"/>,
+    /// returns a window of ±<paramref name="radius"/> chars around it with the terms marked and ellipses
+    /// at the cut points. Empty when nothing matches (so callers can hide the line).
+    /// </summary>
+    public static HtmlString Snippet(string? text, string? query, int radius = 70)
+    {
+        if (string.IsNullOrWhiteSpace(text) || string.IsNullOrWhiteSpace(query)) return HtmlString.Empty;
+        var terms = query.Split(' ', StringSplitOptions.RemoveEmptyEntries | StringSplitOptions.TrimEntries)
+            .Where(t => t.Length >= 2).ToList();
+        if (terms.Count == 0) return HtmlString.Empty;
+
+        var flat = Regex.Replace(text, @"\s+", " ").Trim();
+        int idx = -1, matchLen = 0;
+        foreach (var t in terms)
+        {
+            var i = flat.IndexOf(t, StringComparison.OrdinalIgnoreCase);
+            if (i >= 0 && (idx < 0 || i < idx)) { idx = i; matchLen = t.Length; }
+        }
+        if (idx < 0) return HtmlString.Empty;
+
+        var start = Math.Max(0, idx - radius);
+        var end = Math.Min(flat.Length, idx + matchLen + radius);
+        var slice = flat.Substring(start, end - start).Trim();
+        var prefix = start > 0 ? "…" : "";
+        var suffix = end < flat.Length ? "…" : "";
+        return new HtmlString(prefix + Mark(slice, query).Value + suffix);
+    }
 }