feat(xtream): Xtream playlist refresh workflow

a dedicated refresh button and workflow for Xtream in the
recent playlists UI. Show a refresh icon only when the playlist has a
serverUrl. For Xtream playlists, prompt the user with a confirmation
dialog, delete locally cached categories and streams, show a toast that
the refresh started, and navigate to the playlist to trigger re-import.
Keep existing refresh IPC logic for non-Xtream (M3U/local) playlists.

Also add English translations for the Xtream refresh tooltip and dialog
messages, and surface errors via snackbar on failure.

This enables safe re-importing of remote Xtream playlists while preserving
favorites and recent items.

apps/web/src/assets/i18n/en.json

@@ -54,6 +54,13 @@
             },
             "UPDATED": "Updated",
             "REFRESH": "Refresh playlist",
+            "REFRESH_XTREAM": "Refresh Xtream playlist from remote",
+            "REFRESH_XTREAM_DIALOG": {
+                "TITLE": "Refresh Xtream Playlist",
+                "MESSAGE": "This will delete locally cached categories and streams and re-import everything from the remote server. Your favorites and recently viewed items will be preserved. Are you sure you want to continue?",
+                "STARTED": "Refresh started. Navigating to playlist...",
+                "ERROR": "Failed to refresh playlist. Please try again."
+            },
             "GLOBAL_FAVORITES": "Global favorites",
             "GLOBAL_FAVORITES_DESCRIPTION": "Auto-generated playlist with aggregated favorites from all playlists",
             "MY_PLAYLISTS": "My playlists",