feat: add FFmpeg status check and shutdown button

- FFmpeg check no longer blocks server startup
- Add /api/checkFFmpeg endpoint to query FFmpeg availability
- Add /api/shutdown endpoint to gracefully stop the server
- Add FFmpeg status indicator in web header
- Add shutdown button in web interface
- Move static files output to cmd/bilidown/static for embedding
- Update .gitignore to exclude cmd/bilidown/static

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

cmd/bilidown/main.go

@@ -15,7 +15,7 @@ import (
 	_ "modernc.org/sqlite"
 )
 
-//go:embed all:build/static
+//go:embed all:static
 var staticFiles embed.FS
 
 const (
@@ -25,34 +25,48 @@ const (
 )
 
 var urlLocal = fmt.Sprintf("http://127.0.0.1:%d", HTTP_PORT)
+var ffmpegAvailable bool
 
 func main() {
-	checkFFmpeg()
+	ffmpegAvailable = checkFFmpeg()
 	mustInitTables()
 	mustRunServer()
 	fmt.Printf("Bilidown %s server running at %s\n", VERSION, urlLocal)
+	if !ffmpegAvailable {
+		fmt.Println("Warning: FFmpeg is not installed. Video download will not work.")
+	}
 	select {} // 保持运行
 }
 
-// checkFFmpeg 检测 ffmpeg 的安装情况
-func checkFFmpeg() {
-	if _, err := util.GetFFmpegPath(); err != nil {
-		fmt.Println("FFmpeg is missing. Install it from https://www.ffmpeg.org/download.html, then restart.")
-		os.Exit(1)
-	}
+// checkFFmpeg 检测 ffmpeg 的安装情况，返回是否可用
+func checkFFmpeg() bool {
+	_, err := util.GetFFmpegPath()
+	return err == nil
 }
 
 // mustRunServer 配置和启动 HTTP 服务器
 func mustRunServer() {
 	// 从嵌入的文件系统中获取静态文件
-	staticFS, err := fs.Sub(staticFiles, "build/static")
+	staticFS, err := fs.Sub(staticFiles, "static")
 	if err != nil {
 		log.Fatal("Failed to load static files:", err)
 	}
 	// 前端静态文件
 	http.Handle("/", http.FileServer(http.FS(staticFS)))
 	// 后端 API 接口
-	http.Handle("/api/", http.StripPrefix("/api", router.API()))
+	apiRouter := router.API()
+	// 添加 FFmpeg 状态检查接口
+	http.HandleFunc("/api/checkFFmpeg", func(w http.ResponseWriter, r *http.Request) {
+		util.Res{Success: true, Data: map[string]bool{"available": ffmpegAvailable}}.Write(w)
+	})
+	// 添加关闭服务接口
+	http.HandleFunc("/api/shutdown", func(w http.ResponseWriter, r *http.Request) {
+		util.Res{Success: true, Message: "Shutting down..."}.Write(w)
+		go func() {
+			os.Exit(0)
+		}()
+	})
+	http.Handle("/api/", http.StripPrefix("/api", apiRouter))
 	// 启动 HTTP 服务器
 	go func() {
 		err := http.ListenAndServe(fmt.Sprintf("%s:%d", HTTP_HOST, HTTP_PORT), nil)