Breadcrumbs: visible trail + BreadcrumbList JSON-LD

Add SeoJsonLd.Breadcrumb + Crumb record + _Breadcrumbs partial, and wire a trail
into the Jobs/Shifts list (landing) and detail pages: خانه › استخدام/شیفت › {نقش}
› {شهر|عنوان}. The role crumb links to the role landing page (more internal
links), and Google can show the breadcrumb path in results. Detail pages emit it
alongside the existing JobPosting JSON-LD.

Improvement 5 of the backlog (SEO).

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

src/JobsMedical.Web/wwwroot/css/site.css

@@ -326,6 +326,12 @@ mark { background: #fff3bf; color: inherit; padding: 0 2px; border-radius: 3px;
 .role-links .rl-chip { background: var(--surface); border: 1px solid var(--line); color: var(--ink);
   padding: 5px 12px; border-radius: 999px; font-size: 13px; transition: all .15s; }
 .role-links .rl-chip:hover { border-color: var(--primary); color: var(--primary); }
+/* Breadcrumb trail (paired with BreadcrumbList JSON-LD). */
+.breadcrumbs { font-size: 12.5px; color: var(--muted); margin: 0 0 12px; display: flex; flex-wrap: wrap; gap: 6px; align-items: center; }
+.breadcrumbs a { color: var(--muted); }
+.breadcrumbs a:hover { color: var(--primary); }
+.breadcrumbs .bc-sep { opacity: .55; }
+.breadcrumbs .bc-current { color: var(--ink); font-weight: 600; }
 @media (max-width: 560px) {
   /* Smaller, tighter typography on phones */
   .hero { padding: 28px 0 32px; }