feat: implement collection runs tracking and error acknowledgment features

frontend/index.html

@@ -15,6 +15,7 @@
   <nav class="sidebar-nav">
     <a href="/" class="sidebar-link active">Compte</a>
     <a href="/services" class="sidebar-link">Services</a>
+    <a href="/collecte" class="sidebar-link">Collecte<span class="nav-alert-dot" id="nav-collecte-alert" hidden></span></a>
   </nav>
 </aside>
 <div class="page">
@@ -43,10 +44,6 @@
       <p class="kpi-label">Azure — mois en cours</p>
       <p class="kpi-value" id="kpi-azure">—</p>
     </div>
-    <div class="card kpi-card">
-      <p class="kpi-label">Tenants en échec de collecte</p>
-      <p class="kpi-value" id="kpi-errors">—</p>
-    </div>
   </div>
 
   <p class="section-title">Évolution mensuelle (12 mois glissants)</p>