Refactor filter panels and enhance sidebar functionality

- Updated filter panel toggle icons from chevron-up to chevron-down across multiple pages for consistency.
- Added 'collapsed' class to filter content divs to manage visibility state.
- Enhanced library page button for tidying up media items, replacing the trash icon with a custom SVG broom icon.
- Improved CSS styles for sidebar and page header to ensure visibility and proper layout when the sidebar is collapsed.
- Introduced JavaScript functionality to manage sidebar width and state, including theme toggle for light/dark mode.
- Created a new notification drawer template that adapts based on the compact view state.

custom/otssignange/views/authed-theme-topbar.twig

@@ -3,6 +3,4 @@
   Optional include rendered in authed.twig (top right navbar)
   Minimal, low-risk addition for verification
 #}
-<li class="nav-item ots-theme-badge">
-    <span class="nav-link">OTS Theme</span>
-</li>
+{# OTS topbar badge removed #}