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/volcengine_dns.go

@@ -0,0 +1,37 @@
+package acme
+
+import (
+	"context"
+
+	"github.com/go-acme/lego/v4/challenge"
+	"github.com/go-acme/lego/v4/challenge/dns01"
+
+	"github.com/fonu/fonu/internal/ddns"
+)
+
+type volcengineDNS struct {
+	provider *ddns.Volcengine
+	cred     ddns.Credentials
+}
+
+func newVolcengineDNSProvider(cred ddns.Credentials) (challenge.Provider, error) {
+	if err := cred.Validate("volcengine"); err != nil {
+		return nil, err
+	}
+	return &volcengineDNS{
+		provider: ddns.NewVolcengine(),
+		cred:     cred,
+	}, nil
+}
+
+func (p *volcengineDNS) Present(domain, token, keyAuth string) error {
+	info := dns01.GetChallengeInfo(domain, keyAuth)
+	fqdn := dns01.UnFqdn(info.EffectiveFQDN)
+	return p.provider.UpsertTXTRecord(context.Background(), p.cred, fqdn, info.Value)
+}
+
+func (p *volcengineDNS) CleanUp(domain, token, keyAuth string) error {
+	info := dns01.GetChallengeInfo(domain, keyAuth)
+	fqdn := dns01.UnFqdn(info.EffectiveFQDN)
+	return p.provider.DeleteTXTRecord(context.Background(), p.cred, fqdn, info.Value)
+}