feat(settings): add a Compact buttons appearance toggle (#1189)

* feat(ui): prototype compact hero and toolbar buttons (Large/Small appearance setting)

* feat(settings): rename action-button size toggle to "Compact buttons"

Promote the hero-button prototype to a real, app-wide setting.

- rename heroButtonSize → buttonSize, data-hero-buttons → data-button-size,
  hero-action-bar/hero-btn-label → compact-action-bar/compact-btn-label
- relabel "Hero buttons" → "Compact buttons" and broaden the description
  (action + toolbar buttons across detail pages and browse views) in all 11 locales
- move the feature CSS out of cover-lightbox.css into its own compact-buttons.css
- add tests: themeStore buttonSize toggle, SelectionToggleButton

* docs(changelog): compact buttons appearance toggle (#1189)

* docs(credits): compact buttons appearance toggle (#1189)

src/config/settingsCredits.ts

@@ -387,6 +387,7 @@ const CONTRIBUTOR_ENTRIES = [
       'Per-device equalizer profiles — opt-in, remembers and restores the EQ for each audio output device (PR #1146)',
       'Hungarian (Magyar) translation (PR #1149)',
       'Theme scheduler — follow the OS light/dark setting as an alternative to the time-based day/night schedule (PR #1163)',
+      'Compact buttons — appearance toggle that switches action and toolbar buttons to icon-only across detail headers and browse views, app-wide (PR #1189)',
     ],
   },
   {