feat: add chat log admin management and refactor admin panel to lazy-load tab content

frontend/admin/dashboard.html

@@ -0,0 +1,21 @@
+<h1>Dashboard</h1>
+<div class="stat-grid">
+    <article class="stat-card">
+        <h2>Concurrent Viewers</h2>
+        <p id="stat-viewers" class="stat-value">0</p>
+    </article>
+    <article class="stat-card">
+        <h2>Stored Messages</h2>
+        <p id="stat-stored-messages" class="stat-value">0</p>
+    </article>
+    <article class="stat-card">
+        <h2>Moderation Actions</h2>
+        <p id="stat-moderation-actions" class="stat-value">0</p>
+    </article>
+    <article class="stat-card">
+        <h2>Media Runtime</h2>
+        <p id="stat-media-runtime" class="stat-value">00:00:00</p>
+        <p id="stat-media-count" class="stat-caption">0 files</p>
+    </article>
+</div>
+<p id="overview-status" class="status-line" aria-live="polite">Loading live admin overview...</p>