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

frontend/admin/upload.html

@@ -0,0 +1,41 @@
+<div class="panel-header-row">
+    <div>
+        <h1>Upload Video</h1>
+        <p>Upload media files into the local media library mounted for playout.</p>
+    </div>
+    <button id="reload-media-btn" type="button" class="btn btn-secondary">Reload library</button>
+</div>
+
+<div id="upload-dropzone" class="upload-dropzone">
+    <input type="file" id="video-upload" accept="video/*,.mp4,.mov,.mkv,.webm" hidden />
+    <button id="upload-trigger-btn" type="button" class="btn btn-primary btn-large">Drag and Drop or Click to Upload</button>
+    <p class="small-muted">Resumable chunk upload enabled • up to 2GB per file.</p>
+    <div id="media-upload-progress-wrap" class="upload-progress" hidden>
+        <progress id="media-upload-progress" value="0" max="100"></progress>
+        <p id="media-upload-progress-text" class="small-muted">Uploading (0%)</p>
+    </div>
+    <p id="media-status" class="status-line" aria-live="polite">Loading media library...</p>
+</div>
+
+<div class="panel-card">
+    <div class="panel-header-row">
+        <h2>Media Library</h2>
+        <p id="media-generated-at" class="small-muted">loading...</p>
+    </div>
+    <div class="table-wrap">
+        <table class="data-table">
+            <thead>
+                <tr>
+                    <th>File</th>
+                    <th>Title</th>
+                    <th>Runtime</th>
+                    <th>Status</th>
+                    <th>Size</th>
+                    <th>Modified</th>
+                    <th>Actions</th>
+                </tr>
+            </thead>
+            <tbody id="media-table-body"></tbody>
+        </table>
+    </div>
+</div>