style(nflmusic): 在设置界面将"主题"文本后添加冒号

- 在 ifm_json.py 文件中的 UI 语言设置部分，将"主题"文本从"Theme"改为"Theme:"
- 同时在中文语言设置中，将"主题"改为"主题:"
- 这个修改统一了设置界面各项配置文本的格式，使其更加一致和规范

nflmusic/ifm_json.py

@@ -125,7 +125,7 @@ class Language:
         "ui.download.treeview.song": "歌名",
         "ui.download.treeview.artist": "歌手",
         "ui.download.treeview.album": "专辑",
-        "ui.settings.text.theme": "主题",
+        "ui.settings.text.theme": "主题:",
         "ui.settings.text.download_source": "下载源:",
         "ui.settings.text.download_position": "下载目录:",
         "ui.settings.text.auto_update": "自动更新:",
@@ -240,7 +240,7 @@ class Language:
         "ui.download.treeview.song": "Song Title",
         "ui.download.treeview.artist": "Singer",
         "ui.download.treeview.album": "Album",
-        "ui.settings.text.theme": "Theme",
+        "ui.settings.text.theme": "Theme:",
         "ui.settings.text.download_source": "Download Source:",
         "ui.settings.text.download_position": "Download Catalog:",
         "ui.settings.text.auto_update": "Automatic Update:",