Add localization keys for fallback and status messages in UI

Replaced hardcoded status and fallback messages with localized strings across downloader, update, and main UI modules. Updated language files for all supported languages to include new keys for fallback download status, pip timeout, invalid URL, zero selected, and playlist selection dialog title. This improves internationalization and consistency of user-facing messages.

languages/id.json

@@ -176,7 +176,8 @@
     "please_enter_url": "Silakan masukkan URL terlebih dahulu.",
     "please_set_path": "Silakan atur jalur unduhan terlebih dahulu.",
     "please_enter_url_and_path": "Silakan masukkan URL dan atur jalur unduhan.",
-    "please_select_format": "Silakan pilih format terlebih dahulu."
+    "please_select_format": "Silakan pilih format terlebih dahulu.",
+    "downloading_fallback": "⚡ Mengunduh..."
   },
   "update": {
     "title": "Perbarui yt-dlp",
@@ -208,7 +209,8 @@
     "running_pip_install": "📦 Menjalankan pip install --upgrade...",
     "pip_completed": "✅ Pembaruan pip berhasil diselesaikan!",
     "pip_failed": "❌ Pembaruan pip gagal: {error}",
-    "already_up_to_date": "✅ yt-dlp sudah terbaru!"
+    "already_up_to_date": "✅ yt-dlp sudah terbaru!",
+    "pip_timeout": "❌ Waktu habis untuk pembaruan pip setelah 5 menit"
   },
   "about": {
     "title": "Tentang YTSage",
@@ -307,7 +309,9 @@
     "analyzing_loading_thumbnail_ytdlp": "Menganalisis (85%)... Memuat thumbnail",
     "analyzing_processing_subtitles_ytdlp": "Menganalisis (90%)... Memproses subtitle",
     "select_subtitles": "Pilih subtitle...",
-    "sponsorblock_categories": "Kategori SponsorBlock..."
+    "sponsorblock_categories": "Kategori SponsorBlock...",
+    "invalid_url_or_enter": "URL tidak valid atau silakan masukkan URL.",
+    "zero_selected": "0 dipilih"
   },
   "sponsorblock": {
     "sponsor": "Sponsor",
@@ -374,7 +378,8 @@
   "playlist": {
     "unknown": "Playlist Tidak Dikenal",
     "total_videos": "Total Video: {count}",
-    "display_format": "Playlist: {title} | {count} video"
+    "display_format": "Playlist: {title} | {count} video",
+    "select_videos_title": "Pilih Video Playlist"
   },
   "subtitle_selection": {
     "count_selected": "{count} dipilih"