Remove icons from page title bars and fix Features page issues

- Remove icons from all page title sections in tab bars
- Fix double padding on mobile for Features page
- Fix drag state not resetting when Apply/Cancel pressed

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

frontend/src/pages/admin/ThemeSettings.tsx

@@ -280,7 +280,6 @@ export default function ThemeSettings() {
                         <span className="material-symbols-outlined">menu</span>
                     </button>
                     <div className="page-title-section">
-                        <span className="material-symbols-outlined">brush</span>
                         <span className="page-title-text">{t.theme.title}</span>
                     </div>
                     <div className="admin-tabs-divider"></div>