Continue the design-system unification (kettui UI-consistency item):
migrate the five remaining compact button families onto the shared
.btn .btn--sm primitive + color modifiers, and drop their bespoke base
CSS (net -125 lines of CSS).
- ya-header-btn (Your Albums/Artists, discover.js-injected) -> .btn .btn--sm
.btn--secondary; ya-refresh/ya-settings/ya-viewall co-modifiers kept.
- explorer-action-btn (Playlist Explorer) -> .btn--secondary / .btn--primary.
- repair-bulk-btn -> .btn--secondary / .btn--primary / .btn--warning (fix-all).
- enhanced-bulk-btn (Library bulk bar, library.js-injected) -> .btn--primary/
--secondary/--danger; class kept as a hook for the mobile.css size
override + the .tag-write / .rg-analyze special colors.
- profile-create-btn (init.js-injected) -> .btn .btn--block .btn--primary;
class kept for the scoped .profile-edit-buttons flex:1 rule.
mini-nav-btn deliberately left as a distinct icon-button archetype.