chore: 初始提交 Fonu 1.0.2

- 公网反代：Nginx 状态卡片（版本 / 运行状态 / 配置校验 / 端口监听）
- 部署设置第一、二梯队（HTTPS 开关、安全头、限流、连接数、仅中国大陆 IP）
- 隧道检测兼容 frps v0.68 / v0.71（V2 与旧版端点）
- 恢复被清空的 internal/frp/store.go、internal/api/ddns_handler.go、web/src/views/DdnsView.vue

internal/acme/ca.go

@@ -0,0 +1,89 @@
+package acme
+
+import (
+	"fmt"
+	"strings"
+
+	"github.com/go-acme/lego/v4/lego"
+)
+
+const (
+	CALetsEncrypt        = "letsencrypt"
+	CALetsEncryptStaging = "letsencrypt-staging"
+	CAZeroSSL            = "zerossl"
+	CABuypass            = "buypass"
+)
+
+const (
+	zeroSSLDirectoryURL = "https://acme.zerossl.com/v2/DV90"
+	buypassDirectoryURL = "https://api.buypass.com/acme/directory"
+)
+
+func NormalizeCA(ca string) string {
+	switch ca {
+	case "", CALetsEncrypt, "production":
+		return CALetsEncrypt
+	case CALetsEncryptStaging, "staging", "letsencrypt-test":
+		return CALetsEncryptStaging
+	case CAZeroSSL:
+		return CAZeroSSL
+	case CABuypass, "buypass-go":
+		return CABuypass
+	default:
+		return ca
+	}
+}
+
+func DirectoryURL(ca string) (string, error) {
+	switch NormalizeCA(ca) {
+	case CALetsEncrypt:
+		return lego.LEDirectoryProduction, nil
+	case CALetsEncryptStaging:
+		return lego.LEDirectoryStaging, nil
+	case CAZeroSSL:
+		return zeroSSLDirectoryURL, nil
+	case CABuypass:
+		return buypassDirectoryURL, nil
+	default:
+		return "", fmt.Errorf("不支持的颁发机构：%s", ca)
+	}
+}
+
+func CALabel(ca string) string {
+	switch NormalizeCA(ca) {
+	case CALetsEncrypt:
+		return "Let's Encrypt"
+	case CALetsEncryptStaging:
+		return "Let's Encrypt 测试"
+	case CAZeroSSL:
+		return "ZeroSSL"
+	case CABuypass:
+		return "Buypass"
+	default:
+		if ca == "" {
+			return "手动导入"
+		}
+		return ca
+	}
+}
+
+func ValidateCA(ca string) error {
+	_, err := DirectoryURL(ca)
+	return err
+}
+
+func ValidateCADomains(ca string, domains []string) error {
+	switch NormalizeCA(ca) {
+	case CABuypass:
+		if len(domains) > 5 {
+			return fmt.Errorf("Buypass 单张证书最多支持 5 个域名")
+		}
+		for _, domain := range domains {
+			if strings.HasPrefix(domain, "*.") {
+				return fmt.Errorf("Buypass 不支持通配符证书")
+			}
+		}
+	}
+	return nil
+}
+