feat(folder-browser): keyboard nav, context menus, now-playing path UX

Adds full keyboard navigation (arrow keys, Enter, Ctrl+Enter for context menu) across Folder Browser columns. Context menus for all row types with keyboard-operable submenus and star-rating control via arrow keys + Enter. Now-playing path is visually emphasized and stays stable; rebuilds on hotkey re-invoke or active-path follow-along. Adaptive column layout for deep trees with right-side visibility priority. New configurable 'Open Folder Browser' keybinding. StarRating animation sync for keyboard-driven changes. All 7 locales updated.

src/store/playerStore.ts

@@ -167,7 +167,6 @@ let seekTarget: number | null = null;
 // Guard against rapid double-click play/pause sending two state transitions
 // to the Rust backend before it has finished the previous one.
 let togglePlayLock = false;
-
 /**
  * Skip → 1★: counts in `authStore.skipStarManualSkipCountsByKey` (persisted).
  * Only user-initiated `next()` increments. Natural track end (incl. gapless) clears the count;