feature/hls: Add HLS playback support, and refactors documentation for better usability and maintainability. (#1)

## Overview
This PR introduces HLS playback support, improves the player experience, and refactors documentation for better usability and maintainability.

## Key Features

### HLS Playback Support
- Add HLS integration via new JavaScript assets:
  - `hls.min.js`
  - `plyr.hls.start.js`
  - `watch.hls.js`
- Separate DASH and HLS logic:
  - `plyr-start.js` → `plyr.dash.start.js`
  - `watch.js` → `watch.dash.js`
- Update templates (`embed.html`, `watch.html`) for conditional player loading

### Native Storyboard Preview
- Add `native_player_storyboard` setting in `settings.py`
- Implement hover thumbnail preview for native player modes
- Add `storyboard-preview.js`

### UI and Player Adjustments
- Update templates and styles (`custom_plyr.css`)
- Modify backend modules to support new player modes:
  - `watch.py`, `channel.py`, `util.py`, and related components

### Internationalization
- Update translation files:
  - `messages.po`
  - `messages.pot`

### Testing and CI
- Add and update tests:
  - `test_shorts.py`
  - `test_util.py`
- Minor CI and release script improvements

## Documentation

### OpenRC Service Guide Rewrite
- Restructure `docs/basic-script-openrc/README.md` into:
  - Prerequisites
  - Installation
  - Service Management
  - Verification
  - Troubleshooting
- Add admonition blocks:
  - `[!NOTE]`, `[!TIP]`, `[!IMPORTANT]`, `[!WARNING]`, `[!CAUTION]`
- Fix log inspection command:
  ```bash
  doas tail -f /var/log/ytlocal.log
  ````

* Add path placeholders and clarify permission requirements
* Remove legacy and duplicate content

Reviewed-on: #1
Co-authored-by: Astounds <kirito@disroot.org>
Co-committed-by: Astounds <kirito@disroot.org>

youtube/hls_cache.py

@@ -0,0 +1,23 @@
+"""Multi-audio track support via HLS streaming.
+
+Instead of downloading all segments, we proxy the HLS playlist and
+let the browser stream the audio directly. Zero local storage needed.
+"""
+
+_tracks = {}  # cache_key -> {'hls_url': str, ...}
+
+
+def register_track(cache_key, hls_playlist_url, content_length=0,
+                   video_id=None, track_id=None):
+    print(f'[audio-track-cache] Registering track: {cache_key} -> {hls_playlist_url[:80]}...')
+    _tracks[cache_key] = {'hls_url': hls_playlist_url}
+    print(f'[audio-track-cache] Available tracks: {list(_tracks.keys())}')
+
+
+def get_hls_url(cache_key):
+    entry = _tracks.get(cache_key)
+    if entry:
+        print(f'[audio-track-cache] Found track: {cache_key}')
+    else:
+        print(f'[audio-track-cache] Track not found: {cache_key}')
+    return entry['hls_url'] if entry else None