Allow non-admin users to access dashboard

- Change dashboard route from adminGet to authed middleware
- Show account counts and audit events only for admin users
- Show welcome message for non-admin authenticated users

Security: non-admin users cannot access account lists or audit
events; admin-only data is gated by claims.HasRole("admin") in
the handler, not just at the route level.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

web/templates/dashboard.html

@@ -4,6 +4,7 @@
 <div class="page-header">
   <h1>Dashboard</h1>
 </div>
+{{if .IsAdmin}}
 <div style="display:grid;grid-template-columns:repeat(auto-fit,minmax(200px,1fr));gap:1rem;margin-bottom:1.5rem">
   <div class="card" style="text-align:center">
     <div style="font-size:2rem;font-weight:700;color:#2563eb">{{.TotalAccounts}}</div>
@@ -33,4 +34,9 @@
   </div>
 </div>
 {{end}}
+{{else}}
+<div class="card">
+  <p>Welcome, <strong>{{.ActorName}}</strong>. Use the navigation above to access your profile and credentials.</p>
+</div>
+{{end}}
 {{end}}