fix: resolve golangci-lint errcheck and staticcheck warnings

common/dns_cache.go

@@ -16,7 +16,8 @@ type dnsCache struct {
 // ResolveIP 解析 host 为 *net.IPAddr，结果缓存
 func (c *dnsCache) ResolveIP(host string) (*net.IPAddr, error) {
 	if v, ok := c.m.Load(host); ok {
-		return v.(*net.IPAddr), nil
+		addr, _ := v.(*net.IPAddr)
+		return addr, nil
 	}
 	addr, err := net.ResolveIPAddr("ip", host)
 	if err != nil {

plugins/local/avdetect.go

@@ -107,7 +107,7 @@ func (p *AVDetectPlugin) Scan(ctx context.Context, info *common.HostInfo, sessio
 
 	// 统计结果
 	output.WriteString("=== 检测结果 ===\n")
-	output.WriteString(fmt.Sprintf("检测到的AV产品: %d个\n", len(detectedAVs)))
+	_, _ = fmt.Fprintf(&output, "检测到的AV产品: %d个\n", len(detectedAVs))
 
 	if len(detectedAVs) > 0 {
 		output.WriteString("检测到的产品: " + strings.Join(detectedAVs, ", ") + "\n")

plugins/local/cleaner.go

@@ -44,7 +44,7 @@ func (p *CleanerPlugin) Scan(ctx context.Context, info *common.HostInfo, session
 	for _, file := range files {
 		if p.removeFile(file) {
 			filesCleared++
-			output.WriteString(fmt.Sprintf("清理文件: %s\n", file))
+			_, _ = fmt.Fprintf(&output, "清理文件: %s\n", file)
 		}
 	}
 
@@ -53,7 +53,7 @@ func (p *CleanerPlugin) Scan(ctx context.Context, info *common.HostInfo, session
 	for _, file := range tempFiles {
 		if p.removeFile(file) {
 			filesCleared++
-			output.WriteString(fmt.Sprintf("清理临时文件: %s\n", file))
+			_, _ = fmt.Fprintf(&output, "清理临时文件: %s\n", file)
 		}
 	}