feat(handler,compression): 使用 mimeutil 统一 Content-Type 检测

- 替换 mime.TypeByExtension 为 mimeutil.DetectContentType
- 为 sendfile 大文件路径添加 Content-Type 设置
- 为预压缩文件添加原始 Content-Type
- 添加大文件 Content-Type 测试验证

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

internal/handler/static.go

@@ -19,11 +19,12 @@
 package handler
 
 import (
-	"mime"
 	"os"
 	"path/filepath"
 	"strings"
 
+	"rua.plus/lolly/internal/mimeutil"
+
 	"github.com/valyala/fasthttp"
 	"rua.plus/lolly/internal/cache"
 	"rua.plus/lolly/internal/middleware/compression"
@@ -462,7 +463,7 @@ func (h *StaticHandler) serveFile(ctx *fasthttp.RequestCtx, filePath string, inf
 			if entry.ModTime.Equal(info.ModTime()) {
 				// 缓存命中且文件未修改
 				ctx.Response.SetBody(entry.Data)
-				ctx.Response.Header.SetContentType(mime.TypeByExtension(filepath.Ext(filePath)))
+				ctx.Response.Header.SetContentType(mimeutil.DetectContentType(filePath))
 				return
 			}
 			// 文件已修改，删除旧缓存
@@ -472,6 +473,9 @@ func (h *StaticHandler) serveFile(ctx *fasthttp.RequestCtx, filePath string, inf
 
 	// 大文件使用零拷贝传输
 	if h.useSendfile && info.Size() >= MinSendfileSize {
+		// 设置 Content-Type (sendfile 不会自动设置)
+		ctx.Response.Header.SetContentType(mimeutil.DetectContentType(filePath))
+
 		file, err := os.Open(filePath)
 		if err == nil {
 			defer func() { _ = file.Close() }()
@@ -495,5 +499,5 @@ func (h *StaticHandler) serveFile(ctx *fasthttp.RequestCtx, filePath string, inf
 	}
 
 	ctx.Response.SetBody(data)
-	ctx.Response.Header.SetContentType(mime.TypeByExtension(filepath.Ext(filePath)))
+	ctx.Response.Header.SetContentType(mimeutil.DetectContentType(filePath))
 }

internal/handler/static_test.go

@@ -1402,3 +1402,49 @@ func TestStaticHandler_TryFilesEdgeCases(t *testing.T) {
 		})
 	}
 }
+
+// TestStaticHandler_LargeFileContentType 测试大文件 sendfile 路径的 Content-Type
+func TestStaticHandler_LargeFileContentType(t *testing.T) {
+	tmpDir := t.TempDir()
+
+	// 创建大于 8KB 的文件
+	largeContent := make([]byte, 16*1024)
+	for i := range largeContent {
+		largeContent[i] = byte(i % 256)
+	}
+
+	tests := []struct {
+		ext      string
+		expected string
+	}{
+		{".css", "text/css; charset=utf-8"},
+		{".js", "text/javascript; charset=utf-8"},
+		{".webmanifest", "application/manifest+json"},
+		{".webm", "video/webm"},
+		{".otf", "font/otf"},
+	}
+
+	for _, tc := range tests {
+		t.Run(tc.ext, func(t *testing.T) {
+			filePath := filepath.Join(tmpDir, "large"+tc.ext)
+			if err := os.WriteFile(filePath, largeContent, 0644); err != nil {
+				t.Fatalf("创建文件失败: %v", err)
+			}
+
+			handler := NewStaticHandler(tmpDir, "/", nil, true) // 启用 sendfile
+			ctx := &fasthttp.RequestCtx{}
+			ctx.Request.SetRequestURI("/large" + tc.ext)
+
+			handler.Handle(ctx)
+
+			if got := ctx.Response.StatusCode(); got != fasthttp.StatusOK {
+				t.Errorf("状态码 = %d, want %d", got, fasthttp.StatusOK)
+			}
+
+			ct := string(ctx.Response.Header.ContentType())
+			if ct != tc.expected {
+				t.Errorf("Content-Type = %q, want %q", ct, tc.expected)
+			}
+		})
+	}
+}

internal/middleware/compression/gzip_static.go

@@ -20,6 +20,7 @@ import (
 	"strings"
 
 	"github.com/valyala/fasthttp"
+	"rua.plus/lolly/internal/mimeutil"
 )
 
 // GzipStatic 预压缩文件支持。
@@ -112,6 +113,10 @@ func (g *GzipStatic) ServeFile(ctx *fasthttp.RequestCtx, filePath string) bool {
 			ctx.Response.Header.Set("Content-Encoding", "gzip")
 		}
 		ctx.Response.Header.Set("Vary", "Accept-Encoding")
+		// 设置原始文件的 Content-Type
+		// filePath 是原始文件路径 (如 "test.js")，直接使用即可
+		ctx.Response.Header.SetContentType(mimeutil.DetectContentType(filePath))
+
 		fasthttp.ServeFile(ctx, fullPath)
 		return true
 	}