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/layouts/partials/share-modal.blade.php

@@ -74,6 +74,11 @@ async function openShareModal(videoUrl, videoTitle, recordUrl) {
     var csrfToken = _getLatestCsrf();
     var shareUrl  = videoUrl;
 
+    // Preserve the version selector (?track=) from the requested URL — the server's tracked
+    // share link replaces shareUrl below, so we re-attach it afterwards.
+    var trackParam = '';
+    try { trackParam = (new URL(videoUrl, window.location.origin)).searchParams.get('track') || ''; } catch (e) {}
+
     // Obtain a unique tracked share link from the server
     if (recordUrl) {
         try {
@@ -92,6 +97,11 @@ async function openShareModal(videoUrl, videoTitle, recordUrl) {
         } catch (e) { /* fallback to plain URL */ }
     }
 
+    // Re-attach the version selector so the recipient opens the right language.
+    if (trackParam) {
+        shareUrl += (shareUrl.indexOf('?') === -1 ? '?' : '&') + 'track=' + encodeURIComponent(trackParam);
+    }
+
     // Mobile: use native share sheet with the unique link
     if (window.innerWidth <= 768 && navigator.share) {
         navigator.share({ title: videoTitle, url: shareUrl }).catch(function() {});