The app-wide 'glass over image' tier: panels stay near-opaque (surface 90%, menu 100%)
so chrome text is readable, but glass-card drops to 50% so the per-scheme backdrop image
gently shows through the feed cards (blur 22, inset 10). User-tuned via the live GlassTuner
and validated ("the image just barely shows through, text still readable"); supersedes the
uniform-88% pass that had killed the image-through-cards look. Only the data-backdrop=on
tier — :root (image off) and .glass-media (Plex art) unchanged.