Refactor FFmpeg updater to version checker

Replaces the FFmpeg updater logic with a version checker across all supported languages and removes the updater module. The Windows installation logic in ytsage_ffmpeg.py is rewritten to use essentials build extraction and path configuration directly, removing dependency on the updater module. Dialogs and UI strings are updated to reflect the new version checking workflow and provide installation guide links.

languages/zh.json

@@ -477,22 +477,17 @@
     "redownload_started": "已开始下载"
   },
   "ffmpeg_updater": {
-    "title": "FFmpeg 更新器",
+    "title": "FFmpeg 版本检查器",
     "current_version": "当前版本：",
     "latest_version": "最新版本：",
     "status_up_to_date": "✓ 已是最新",
     "status_update_available": "⚠ 有可用更新",
     "status_not_installed": "✗ 未安装",
-    "status_checking": "🔄 正在检查更新...",
-    "status_downloading": "⬇ 正在下载 FFmpeg...",
-    "status_installing": "⚙ 正在安装 FFmpeg...",
-    "status_verifying": "✓ 正在验证完整性...",
-    "check_updates": "检查更新",
-    "update_button": "更新 FFmpeg",
-    "update_success": "FFmpeg 已成功更新到版本 {version}！",
-    "update_failed": "更新 FFmpeg 失败。请重试。",
-    "check_failed": "检查更新失败。请检查您的网络连接。",
-    "install_first": "FFmpeg 未安装。点击更新以安装。",
-    "description": "保持 FFmpeg 更新以获得最佳性能和兼容性。"
+    "status_idle": "点击「检查版本」开始",
+    "status_checking": "🔄 正在检查版本...",
+    "check_updates": "检查版本",
+    "check_failed": "检查版本失败。请检查您的网络连接。",
+    "description": "检查您的 FFmpeg 版本并与最新可用版本进行比较。",
+    "guide_info": " 要安装或更新 FFmpeg，<a href='https://github.com/oop7/ffmpeg-install-guide'>请点击此处查看我们的综合安装指南</a>。"
   }
 }