[Nav] Add ثبت آگهی CTA, streamline menu, active-link highlight, role dashboards

Header gets a prominent accent ＋ثبت آگهی CTA → /Employer/Index (auth redirect handles login → register/post). Main nav trimmed to the 5 core public links (خانه/شیفت‌ها/استخدام/مراکز/تقویم); دریافت اپ + راهنما live in the footer and علاقه‌مندی‌ها in the profile menu, so the bar is far less crowded. Added active-page highlight (accent underline on desktop, soft background on mobile). Login now sends admins to /Admin/Overview (dashboard) instead of the ingestion queue; employers→/Employer/Index, job-seekers→/Me already in place.

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

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

@@ -64,8 +64,14 @@ a { color: inherit; text-decoration: none; }
    and the whole thing can collapse into a dropdown on mobile. */
 .nav-collapse { display: flex; align-items: center; gap: 18px; flex: 1; }
 .main-nav { display: flex; gap: 18px; margin-inline-start: 6px; flex: 1; }
-.main-nav a { color: var(--muted); font-weight: 600; font-size: 15px; white-space: nowrap; transition: color .15s; }
+.main-nav a { color: var(--muted); font-weight: 600; font-size: 15px; white-space: nowrap; transition: color .15s; position: relative; padding: 4px 0; }
 .main-nav a:hover { color: var(--primary); }
+.main-nav a.active { color: var(--primary-dark); }
+.main-nav a.active::after {
+  content: ""; position: absolute; inset-inline: 0; bottom: -6px; height: 2px;
+  background: var(--accent); border-radius: 2px;
+}
+.cta-post { white-space: nowrap; box-shadow: 0 2px 8px rgba(240,132,62,.35); }
 .header-actions { display: flex; align-items: center; gap: 12px; margin-inline-start: auto; }
 .nav-action { font-weight: 600; font-size: 15px; color: var(--muted); white-space: nowrap; transition: color .15s; }
 .nav-action:hover { color: var(--primary); }
@@ -439,6 +445,8 @@ label { font-size: 13px; }
 
   .main-nav { flex-direction: column; gap: 0; margin: 0; flex: none; padding: 6px 0; }
   .main-nav a { padding: 13px 20px; font-size: 15px; border-bottom: 1px solid var(--line); }
+  .main-nav a.active::after { display: none; }
+  .main-nav a.active { background: var(--primary-soft); border-radius: 8px; }
   .main-nav a:last-child { border-bottom: none; }
 
   .header-actions {