feat(command-palette): add recently used section and switch-player commands

Adds a "Recently used" section at the top of the command palette (capped at 5,
persisted via StorageMap) and five "Switch player to ..." commands for one-step
player switching from anywhere. MPV/VLC are gated to Electron; the active player
entry is shown disabled. Switching applies to the next playback session.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
Entire-Checkpoint: c2cea9c530e6

libs/shared/interfaces/src/lib/store-keys.enum.ts

@@ -1,5 +1,6 @@
 /** Labels of properties in local storage */
 export enum STORE_KEY {
     Settings = 'settings',
-    Version = 'version'
+    Version = 'version',
+    RecentCommands = 'recent-commands',
 }