feat: Add winners tab and 100% completion stats

Adds a new section to the admin control panel for managing yearly winners.
Also includes a new section on the user statistics page to display users
who have completed 100% of movies for each year.

Co-authored-by: mathieumoran1 <[email protected]>

public/user-stat.html

@@ -62,6 +62,24 @@
 <div class="container mt-5">
   <h2>Statistiques des utilisateurs</h2>
   
+  <!-- Winners section -->
+  <div class="mt-4">
+    <h4 class="mb-2">Gagnants</h4>
+    <div class="text-muted mb-2">Définis dans l’admin (optionnel).</div>
+    <div id="winners-list" class="list-group mb-4">
+      <div class="list-group-item text-muted">Chargement…</div>
+    </div>
+  </div>
+
+  <!-- 100% completers section -->
+  <div class="mt-4">
+    <h4 class="mb-2">Utilisateurs ayant terminé 100% (par année)</h4>
+    <div class="text-muted mb-2">Completion = 100% pour l’année (tous les films de l’année vus).</div>
+    <div id="completers-by-year" class="mb-4">
+      <div class="text-muted">Chargement…</div>
+    </div>
+  </div>
+
   <!-- Spinner shown while loading -->
   <div id="loading-spinner" class="spinner-border text-primary" role="status">
     <span class="visually-hidden">Loading...</span>