Fix: Settings section gears permanently hijacked the active tab

The folder and tag section gears in the sidebar deep-linked into Settings by writing the persisted `settings-active-tab` localStorage key, so the chosen section became the permanent default the main Settings button opened on - indefinitely.

Compounding it, the desktop Settings tab list called setActiveTab directly without persisting, so normal navigation never updated the default and the hijacked value could never self-correct.

Fix: section gears now write a one-shot sessionStorage key that is consumed on mount (transient deep-link, no persistence); desktop tab clicks go through handleTabSelect like the mobile list, so the last-used tab is saved consistently. Stale/removed tab IDs are still caught by the existing effectiveActiveTab fallback.

components/layout/sidebar.tsx

@@ -904,11 +904,11 @@ export function Sidebar({
   };
 
   const openFolderSettings = () => {
-    try { localStorage.setItem('settings-active-tab', 'folders'); } catch { /* */ }
+    try { sessionStorage.setItem('settings-deep-link-tab', 'folders'); } catch { /* */ }
     router.push('/settings');
   };
   const openKeywordSettings = () => {
-    try { localStorage.setItem('settings-active-tab', 'keywords'); } catch { /* */ }
+    try { sessionStorage.setItem('settings-deep-link-tab', 'keywords'); } catch { /* */ }
     router.push('/settings');
   };