implemented the lower priority features; haven't tested them

frontend/src/App.tsx

@@ -10,6 +10,8 @@ import DevPanel from './components/DevPanel';
 import MarkersPanel from './components/MarkersPanel';
 import SilenceTrimmerPanel from './components/SilenceTrimmerPanel';
 import ZoneEditor from './components/ZoneEditor';
+import BackgroundMusicPanel from './components/BackgroundMusicPanel';
+import AppendClipPanel from './components/AppendClipPanel';
 import { useKeyboardShortcuts } from './hooks/useKeyboardShortcuts';
 import {
   Film,
@@ -27,11 +29,13 @@ import {
   RefreshCw,
   Grid3x3,
   MapPin,
+  Music,
+  ListVideo,
 } from 'lucide-react';
 
 const LAST_MEDIA_PATH_KEY = 'talkedit:lastMediaPath';
 
-type Panel = 'ai' | 'settings' | 'export' | 'silence' | 'zones' | 'markers' | null;
+type Panel = 'ai' | 'settings' | 'export' | 'silence' | 'zones' | 'markers' | 'music' | 'append' | null;
 
 export default function App() {
   const {
@@ -654,6 +658,20 @@ export default function App() {
             onClick={() => togglePanel('markers')}
             disabled={!videoPath}
           />
+          <ToolbarButton
+            icon={<Music className="w-4 h-4" />}
+            label="Music"
+            active={activePanel === 'music'}
+            onClick={() => togglePanel('music')}
+            disabled={!videoPath}
+          />
+          <ToolbarButton
+            icon={<ListVideo className="w-4 h-4" />}
+            label="Append"
+            active={activePanel === 'append'}
+            onClick={() => togglePanel('append')}
+            disabled={!videoPath}
+          />
           <div className="flex items-center gap-1.5 px-2 py-1 rounded-md bg-editor-surface border border-editor-border">
             <select
               value={whisperModel}
@@ -812,6 +830,8 @@ export default function App() {
             )}
             {activePanel === 'silence' && <SilenceTrimmerPanel />}
             {activePanel === 'markers' && <MarkersPanel />}
+            {activePanel === 'music' && <BackgroundMusicPanel />}
+            {activePanel === 'append' && <AppendClipPanel />}
             {activePanel === 'ai' && <AIPanel />}
             {activePanel === 'export' && <ExportDialog />}
             {activePanel === 'settings' && <SettingsPanel />}