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/nginx/config_validate.go

@@ -0,0 +1,75 @@
+package nginx
+
+import (
+	"fmt"
+	"strings"
+)
+
+func certUsable(cert *certFiles) bool {
+	if cert == nil {
+		return false
+	}
+	if strings.TrimSpace(cert.CertPath) == "" || strings.TrimSpace(cert.KeyPath) == "" {
+		return false
+	}
+	return fileExists(cert.CertPath) && fileExists(cert.KeyPath)
+}
+
+func assertValidSSLBlocks(content string) error {
+	inServer := false
+	depth := 0
+	serverSSL := false
+	serverCert := false
+
+	for _, raw := range strings.Split(content, "\n") {
+		line := strings.TrimSpace(raw)
+		if line == "" || strings.HasPrefix(line, "#") {
+			continue
+		}
+
+		if !inServer {
+			if strings.HasPrefix(line, "server") && strings.Contains(line, "{") {
+				inServer = true
+				depth = braceDelta(line)
+				serverSSL = false
+				serverCert = false
+			}
+			continue
+		}
+
+		depth += braceDelta(line)
+		if isSSLListenLine(line) {
+			serverSSL = true
+		}
+		if isSSLCertificateLine(line) {
+			serverCert = true
+		}
+
+		if depth <= 0 {
+			if serverSSL && !serverCert {
+				return fmt.Errorf("检测到未配置证书的 HTTPS 监听，请为域名申请或导入证书，或关闭 HTTPS")
+			}
+			inServer = false
+		}
+	}
+
+	if inServer && serverSSL && !serverCert {
+		return fmt.Errorf("检测到未配置证书的 HTTPS 监听，请为域名申请或导入证书，或关闭 HTTPS")
+	}
+	return nil
+}
+
+func braceDelta(line string) int {
+	return strings.Count(line, "{") - strings.Count(line, "}")
+}
+
+func isSSLListenLine(line string) bool {
+	if !strings.HasPrefix(line, "listen ") {
+		return false
+	}
+	return strings.Contains(line, " ssl;") || strings.HasSuffix(line, " ssl")
+}
+
+func isSSLCertificateLine(line string) bool {
+	return strings.HasPrefix(line, "ssl_certificate ") && !strings.HasPrefix(line, "ssl_certificate_key ")
+}