i18n(favorites): translate empty states, loading, and headers

- Add t import and use translations for all empty state messages
- Translate loading states (favorites, playlists, albums)
- Translate section headers (Discography, EPs & Singles, Live Albums)
- Translate button titles (Play All, Shuffle, More, Search, Clear)
- Add hint translations for liking items to favorites
- Update getSortLabel to use sort.* translation keys
- Update getTabLabel to use favorites.tabLabels.* keys

cc

src/lib/i18n/locales/en.json

@@ -264,7 +264,27 @@
     "albums": "Albums",
     "tracks": "Tracks",
     "artists": "Artists",
+    "playlists": "Playlists",
     "noFavorites": "No favorites yet",
+    "noFavoriteTracks": "No favorite tracks yet",
+    "noFavoriteAlbums": "No favorite albums yet",
+    "noFavoriteArtists": "No favorite artists yet",
+    "noFavoritePlaylists": "No favorite playlists yet",
+    "noTracksMatch": "No tracks match \"{query}\"",
+    "noAlbumsMatch": "No albums match \"{query}\"",
+    "noArtistsMatch": "No artists match \"{query}\"",
+    "noPlaylistsMatch": "No playlists match \"{query}\"",
+    "noAlbumsFound": "No albums found",
+    "likeTracksHint": "Like tracks to see them here",
+    "likeAlbumsHint": "Like albums to see them here",
+    "likeArtistsHint": "Like artists to see them here",
+    "likePlaylistsHint": "Click the heart icon on playlists to add them here",
+    "selectArtistHint": "Select an artist to see their albums",
+    "loadingAlbums": "Loading albums...",
+    "failedLoadAlbums": "Failed to load albums",
+    "failedLoadFavorites": "Failed to load favorites",
+    "loadingFavorites": "Loading favorites...",
+    "loadingPlaylists": "Loading playlists...",
     "addedToFavorites": "Added to favorites",
     "removedFromFavorites": "Removed from favorites",
     "editSettings": "Edit Favorites Settings",
@@ -286,6 +306,23 @@
     "saving": "Saving...",
     "cancel": "Cancel"
   },
+  "placeholders": {
+    "search": "Search...",
+    "searchDevices": "Search devices...",
+    "searchGenres": "Search genres...",
+    "searchFolders": "Search folders...",
+    "searchPlaylists": "Search playlists...",
+    "searchAlbums": "Search albums...",
+    "searchInPage": "Search in this page...",
+    "searchInPlaylist": "Search in playlist...",
+    "filterFolders": "Filter folders...",
+    "myPlaylist": "My Playlist",
+    "addDescription": "Add a description...",
+    "enterFolderName": "Enter folder name",
+    "enterApiKey": "Enter your API key",
+    "enterSharedSecret": "Enter your shared secret",
+    "pasteToken": "Paste your ListenBrainz token"
+  },
   "player": {
     "nowPlaying": "Now Playing",
     "queue": "Queue",