Add user list to admin panel and validated/guest badges on posts

Admin panel: new "Käyttäjät" section showing all registered users with
post count, likes count, email and join date.

Posts: submissions by logged-in users show a green "Vahvistettu" badge,
while guest submissions show a random code (e.g. #L01U51) for tracking.

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

admin.html

@@ -159,6 +159,14 @@
     .cat-info { flex: 1; font-family: Arial, sans-serif; font-size: 0.88rem; color: #3b2a1a; }
     .cat-info span { color: #7a5c3e; font-size: 0.78rem; }
 
+    /* User list */
+    .user-table { width: 100%; border-collapse: collapse; font-family: Arial, sans-serif; font-size: 0.88rem; }
+    .user-table th { text-align: left; color: #7a5c3e; font-size: 0.75rem; text-transform: uppercase; letter-spacing: 0.5px; padding: 6px 10px; border-bottom: 2px solid #e8d5c0; }
+    .user-table td { padding: 9px 10px; border-bottom: 1px solid #f0e8dc; color: #3b2a1a; }
+    .user-table tr:last-child td { border-bottom: none; }
+    .user-table .user-nick { font-weight: bold; color: #7c4a1e; }
+    .user-table .badge { display: inline-block; background: #f0e8dc; color: #7a5c3e; padding: 2px 8px; border-radius: 10px; font-size: 0.78rem; }
+
     .empty-state { text-align: center; color: #7a5c3e; font-style: italic; padding: 20px 0; }
 
     .toast {
@@ -340,9 +348,15 @@
       </section>
     </div>
 
-    <!-- RIGHT: Categories + Post list -->
+    <!-- RIGHT: Users + Categories + Post list -->
     <div class="section-right">
 
+      <!-- USERS -->
+      <section class="admin-panel">
+        <h2>Käyttäjät</h2>
+        <div id="userList"><p class="empty-state">Ladataan...</p></div>
+      </section>
+
       <!-- CATEGORIES -->
       <section class="admin-panel">
         <h2 id="lbl_categories">Kategoriat</h2>
@@ -454,17 +468,20 @@
     }
 
     async function loadAdminData() {
-      const [postsData, catsData] = await Promise.all([
+      const [postsData, catsData, usersData] = await Promise.all([
         apiGet('posts'),
         apiGet('categories'),
+        apiGet('admin_users'),
       ]);
       ADMIN.posts      = postsData.posts      || [];
       ADMIN.categories = catsData.categories  || [];
+      ADMIN.users      = usersData.users      || [];
       document.getElementById('backLink').textContent = at('back');
       document.getElementById('saveBtn').textContent  = at('save');
       populateCategorySelect();
       renderCatList();
       renderPostList();
+      renderUserList();
     }
 
     // ===========================
@@ -803,6 +820,28 @@
       });
     }
 
+    // ===========================
+    // USER LIST
+    // ===========================
+    function renderUserList() {
+      const users = ADMIN.users || [];
+      const el = document.getElementById('userList');
+      if (!users.length) { el.innerHTML = '<p class="empty-state">Ei rekisteröityneitä käyttäjiä.</p>'; return; }
+      el.innerHTML = `
+        <table class="user-table">
+          <thead><tr><th>Nimimerkki</th><th>Sähköposti</th><th>Julkaisut</th><th>Tykkäykset</th><th>Liittynyt</th></tr></thead>
+          <tbody>${users.map(u => `
+            <tr>
+              <td class="user-nick">${u.nickname}</td>
+              <td>${u.email || '<span style="color:#bbb">–</span>'}</td>
+              <td><span class="badge">${u.postCount}</span></td>
+              <td><span class="badge">${u.likes}</span></td>
+              <td>${u.created || '–'}</td>
+            </tr>`).join('')}
+          </tbody>
+        </table>`;
+    }
+
     // ===========================
     // TOAST
     // ===========================