Audio songs: one-folder storage, version-aware download/share, GPU-checked renders

Storage structure
- All audio tracks (primary + per-language) now live in one folder per song with
  unique lowercase names ({slug}-{lang}-{id}); no more tracks/ subfolder.
- Generated renders (download video + HLS) moved into the song's local-only cache/
  subfolder, separated from source files (never synced to NAS, safe to wipe).
- tracks:reorganize artisan command (dry-run default) consolidates legacy files,
  updates DB paths, and deletes orphans + empty folders.
- CLAUDE.md documents the canonical layout as a global rule (identical local + NAS).

Version-aware download & share
- Download MP3/Video and Share now act on the version being played; ?track={id}
  is carried through share links and auto-selects audio + title + flag + about +
  OG/meta on open.

GPU + visualizer
- Setting::gpuUsable() runs a cached health probe (nvidia-smi + nvenc smoke test,
  256x144) before sending any encode to the GPU; falls back to CPU otherwise.
- Visualizer "Download Video" bakes in equal-width, cover-coloured, translucent
  frequency bars; loop-filter rebuild makes generation ~25x faster.

Image cropper
- result-callback mode + per-song cover-slide cropper in upload/edit (modal + mobile).

Co-Authored-By: Claude Opus 4.7 (1M context) <[email protected]>

resources/views/components/track-editor-form.blade.php

@@ -207,15 +207,10 @@
         </div>
     </div>
 
-    {{-- ── Description ────────────────────────────────────────────── --}}
+    {{-- ── Description (rich text) ────────────────────────────────── --}}
     <div class="um-field">
         <label class="um-lbl" style="font-size:10px;margin-bottom:6px;">Description @if(!$isPrimary)<span class="um-lbl-hint">optional</span>@endif</label>
-        <textarea name="{{ $descName }}"
-                  id="{{ $descId }}"
-                  class="um-input um-textarea"
-                  rows="3"
-                  style="font-size:13px;padding:9px 12px;"
-                  placeholder="Tell viewers about this content…"></textarea>
+        <x-rich-text-editor :name="$descName" :id="$descId" placeholder="Tell viewers about this content…" />
     </div>
 
     {{-- ── Video file + Thumbnail (video / match mode, primary only) ── --}}