perf: 添加gzip压缩提升前端资源加载速度

- 对JS/CSS/HTML/JSON/SVG等文本资源启用gzip压缩
- 传输体积可减少70-80%，大幅提升页面加载速度
- 图片和字体等已压缩格式不重复压缩

backend/cmd/main.go

@@ -1,6 +1,7 @@
 package main
 
 import (
+	"compress/gzip"
 	"embed"
 	"fmt"
 	"io/fs"
@@ -273,9 +274,19 @@ func setupEmbeddedFrontend(r *gin.Engine) {
 		}
 
 		contentType := getContentType(decodedPath)
-
 		c.Header("Cache-Control", "public, max-age=31536000, immutable")
-		c.Data(200, contentType, data)
+
+		if strings.Contains(c.GetHeader("Accept-Encoding"), "gzip") && isCompressible(decodedPath) {
+			c.Header("Content-Encoding", "gzip")
+			c.Header("Vary", "Accept-Encoding")
+			c.Writer.WriteHeader(200)
+			c.Writer.Header().Set("Content-Type", contentType)
+			gw := gzip.NewWriter(c.Writer)
+			gw.Write(data)
+			gw.Close()
+		} else {
+			c.Data(200, contentType, data)
+		}
 	})
 
 	r.NoRoute(func(c *gin.Context) {
@@ -334,6 +345,16 @@ func getSettingString(settings map[string]interface{}, key, defaultValue string)
 	return defaultValue
 }
 
+func isCompressible(filename string) bool {
+	ext := strings.ToLower(filename[strings.LastIndex(filename, "."):])
+	switch ext {
+	case ".js", ".mjs", ".css", ".html", ".json", ".svg", ".xml", ".txt":
+		return true
+	default:
+		return false
+	}
+}
+
 func getContentType(filename string) string {
 	ext := strings.ToLower(filename[strings.LastIndex(filename, "."):])
 	switch ext {