feat(ui): add unified Sources & Destinations integrations dashboard

Co-authored-by: christianlouis <361235+christianlouis@users.noreply.github.com>

frontend/templates/base.html

@@ -111,6 +111,11 @@
                {% if request and request.url.path == '/imap-accounts' %}aria-current="page"{% endif %}>
               <i class="fas fa-envelope-open-text mr-1 text-gray-400" aria-hidden="true"></i>Email Ingestion
             </a>
+            <a href="/integrations"
+               class="px-3 py-2 rounded-md text-sm font-medium text-gray-700 hover:text-gray-900 hover:bg-gray-100"
+               {% if request and request.url.path == '/integrations' %}aria-current="page"{% endif %}>
+              <i class="fas fa-plug mr-1 text-gray-400" aria-hidden="true"></i>Integrations
+            </a>
 
             <!-- Admin dropdown – shown only for admin users via JS -->
             <div id="adminMenuContainer" class="relative hidden">
@@ -276,6 +281,11 @@
                  {% if request and request.url.path == '/imap-accounts' %}aria-current="page"{% endif %}>
                 <i class="fas fa-envelope-open-text mr-2 text-gray-400" aria-hidden="true"></i>Email Ingestion
               </a>
+              <a href="/integrations"
+                 class="block px-3 py-3 rounded-md text-base font-medium text-gray-700 hover:text-gray-900 hover:bg-gray-50"
+                 {% if request and request.url.path == '/integrations' %}aria-current="page"{% endif %}>
+                <i class="fas fa-plug mr-2 text-gray-400" aria-hidden="true"></i>Integrations
+              </a>
 
               <!-- Admin section in mobile menu – shown only for admin users via JS -->
               <div id="mobileAdminSection" class="hidden">