Support multiple portal credentials per registration

app/modules/credential_vault/templates/credential_vault/form.html

@@ -4,13 +4,13 @@
   <div class="mb-5">
     <h1 class="text-2xl font-bold">Add encrypted credential</h1>
     {% if selected_registration %}
-    <p class="mt-1 text-sm text-slate-600">Linked to registration <strong>{{ selected_registration.registration_number }}</strong>. Secrets remain encrypted and reveal access is audited.</p>
+    <p class="mt-1 text-sm text-slate-600">Linked to registration <strong>{{ selected_registration.registration_number }}</strong>. You can save multiple independent portal credentials for the same registration (for example Income Tax Portal and TRACES for one TAN). Secrets remain encrypted and reveal access is audited.</p>
     {% endif %}
   </div>
   <form method="post" class="grid gap-4 rounded-xl bg-white p-6 shadow sm:grid-cols-2">
     <input type="hidden" name="csrf_token" value="{{ csrf_token }}">
     <label class="sm:col-span-2">Title<input required name="title" class="mt-1 w-full rounded-lg border p-2" placeholder="e.g. GST Portal - Main Login"></label>
-    <label>Credential type
+    <label>Portal / credential type
       <select name="category" class="mt-1 w-full rounded-lg border p-2">
         <option value="gst_portal">GST Portal</option>
         <option value="income_tax_portal">Income Tax Portal</option>
@@ -26,6 +26,7 @@
         <option value="digital_signature">Digital signature</option>
         <option value="other">Other</option>
       </select>
+      <span class="mt-1 block text-xs text-slate-500">Each portal is stored as a separate vault entry. Adding TRACES does not replace the Income Tax Portal credential for the same TAN.</span>
     </label>
     <label>Sensitivity<select name="sensitivity" class="mt-1 w-full rounded-lg border p-2"><option>high</option><option>critical</option><option>standard</option></select></label>
     <label>Client