fix(ssf): 修复安全事件连接基础阻断

为已记录旧迁移版本的环境补充幂等表修复迁移，并让 Transmitter 网络连接在 IPv6 地址不可达时继续尝试 IPv4。失败连接现在通过 If-Match 安全重试，页面同步提供重试入口并清理过期错误提示。\n\n验证：Go securityevents/migrate 测试、Web Vitest 与 TypeScript 类型检查通过。

apps/api/internal/securityevents/connection_manager.go

@@ -879,11 +879,26 @@ func safeHTTPClient(issuer *url.URL, appEnv string) *http.Client {
 			}
 		}
 		dialer := &net.Dialer{Timeout: 5 * time.Second}
-		return dialer.DialContext(ctx, network, net.JoinHostPort(addresses[0].IP.String(), port))
+		return dialResolvedAddresses(ctx, network, port, addresses, dialer)
 	}
 	return &http.Client{Timeout: 10 * time.Second, Transport: transport, CheckRedirect: func(*http.Request, []*http.Request) error { return http.ErrUseLastResponse }}
 }
 
+func dialResolvedAddresses(ctx context.Context, network, port string, addresses []net.IPAddr, dialer *net.Dialer) (net.Conn, error) {
+	var attempts []error
+	for _, address := range addresses {
+		connection, err := dialer.DialContext(ctx, network, net.JoinHostPort(address.IP.String(), port))
+		if err == nil {
+			return connection, nil
+		}
+		attempts = append(attempts, err)
+		if ctx.Err() != nil {
+			break
+		}
+	}
+	return nil, fmt.Errorf("transmitter connection failed for every resolved address: %w", errors.Join(attempts...))
+}
+
 func blockedAddress(ip net.IP) bool {
 	if ip.IsLoopback() || ip.IsPrivate() || ip.IsLinkLocalUnicast() || ip.IsLinkLocalMulticast() ||
 		ip.IsUnspecified() || ip.IsMulticast() {