refactor(ui): consolidate unified-sidebar into sidebar folder

Merge the unified-sidebar implementation into the standard sidebar
folder structure. The unified sidebar becomes the canonical sidebar
with improved features including collapsible sections, scroll
indicators, and enhanced mobile support.

- Delete old sidebar.tsx
- Move unified-sidebar components to sidebar/components
- Rename UnifiedSidebar to Sidebar
- Update all imports in __root.tsx
- Remove redundant unified-sidebar folder

apps/ui/src/routes/__root.tsx

@@ -3,7 +3,7 @@ import { useEffect, useState, useCallback, useDeferredValue, useRef } from 'reac
 import { QueryClientProvider } from '@tanstack/react-query';
 import { ReactQueryDevtools } from '@tanstack/react-query-devtools';
 import { createLogger } from '@automaker/utils/logger';
-import { UnifiedSidebar } from '@/components/layout/unified-sidebar';
+import { Sidebar } from '@/components/layout/sidebar';
 import {
   FileBrowserProvider,
   useFileBrowser,
@@ -860,7 +860,7 @@ function RootLayoutContent() {
             aria-hidden="true"
           />
         )}
-        <UnifiedSidebar />
+        <Sidebar />
         <div
           className="flex-1 flex flex-col overflow-hidden transition-all duration-300"
           style={{ marginRight: streamerPanelOpen ? '250px' : '0' }}