docs(help): add 11 new FAQ entries for undocumented features

Ratings (q37-q39): how to rate songs/albums/artists, click active star to
remove rating, Skip-to-1★ and rating filter for mixes. Folder Browser (q40).
Settings: Theme Scheduler (q41), UI Scale (q42), Seekbar styles (q43),
AutoEQ (q44), Replay Gain (q45), Hot Cache (q46). Offline: playlist
caching and toggle (q47). All 7 locales updated.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/locales/en.ts

@@ -669,6 +669,28 @@ export const enTranslation = {
     a35: 'Open any album and click the download icon in the album header. Psysonic downloads all tracks in the background. Progress is shown on the button. Once cached, the icon turns green. You can view and remove cached albums in the Offline Library page (sidebar).',
     q36: 'How much storage can offline caching use?',
     a36: 'You can set a maximum cache size in Settings → Library. When the limit is reached, a warning banner appears on the album page. You can delete individual albums from the Offline Library to free up space.',
+    q37: 'How do I rate songs, albums, and artists?',
+    a37: 'Psysonic supports 1–5 star ratings via the OpenSubsonic API (requires Navidrome ≥ 0.53). Rate songs in the album or playlist track list using the star column, in the right-click context menu, or directly in the player bar below the artist name. Albums can be rated on their detail page; artists on their artist page. Ratings are saved to the server immediately.',
+    q38: 'Can I remove or change a rating?',
+    a38: 'Yes. Click the currently active star to clear the rating entirely — clicking the same star a second time removes it. To change a rating, simply click a different star.',
+    q39: 'What is Skip-to-1★ and the rating filter?',
+    a39: 'Skip-to-1★ automatically assigns a 1-star rating to a song after you manually skip it a configurable number of consecutive times. Enable it and set the skip threshold in Settings → Ratings. The same settings panel lets you set a minimum star rating for Random Mix and Random Albums, so only songs, albums, or artists above a certain rating are included in generated mixes.',
+    q40: 'What is the Folder Browser?',
+    a40: 'The Folder Browser (sidebar) lets you navigate your server\'s music directory tree using a Miller-column layout. Click a folder to drill into it; click a track or the play icon on a folder to play or enqueue its contents directly.',
+    q41: 'What is the Theme Scheduler?',
+    a41: 'Settings → Appearance → Auto-Switch Theme: define a day theme and a night theme with start times. Psysonic switches automatically at the configured hours. When the scheduler is active, a hint in the theme picker explains why manual theme selection has no immediate effect.',
+    q42: 'Can I resize the interface?',
+    a42: 'Yes. Settings → Appearance → Interface Scale lets you scale the entire UI between 80 % and 125 % without affecting your system font size.',
+    q43: 'Can I change the seekbar style?',
+    a43: 'Yes. Settings → Appearance → Seekbar Style offers 10 styles: Waveform, Line & Dot, Bar, Thick Bar, Segmented, Neon Glow, Pulse Wave, Particle Trail, Liquid Fill, and Retro Tape.',
+    q44: 'What is AutoEQ?',
+    a44: 'The 10-band EQ in Settings → Audio includes an AutoEQ lookup. Enter your headphone model and Psysonic fetches a correction profile from the AutoEQ database and applies it automatically to the equalizer bands.',
+    q45: 'What is Replay Gain?',
+    a45: 'Replay Gain normalizes track volume so loud and quiet albums play at a consistent level. Enable it in Settings → Audio → Replay Gain and choose Track mode (per-song normalization) or Album mode (preserves relative dynamics within an album).',
+    q46: 'What is the Hot Cache?',
+    a46: 'Hot Cache (Alpha, Settings → Library) preloads the next several tracks in your queue to disk so playback starts instantly with no buffering delay — especially useful on slow or remote servers. Psysonic keeps the current track and the next 5 in cache and evicts older entries when the size limit is reached. You can set the maximum cache size and a debounce delay to avoid unnecessary fetches when skipping quickly.',
+    q47: 'Can I cache a playlist for offline use?',
+    a47: 'Yes. Open any playlist and click the download icon in the playlist header. All tracks are downloaded in the background — progress is shown in the offline download indicator. Once fully cached, the icon changes to a red trash icon; clicking it removes the playlist from the offline cache.',
   },
   queue: {
     title: 'Queue',