/**
 * Convert a UTC datetime string to a plain datetime string in the format "YYYY-MM-DDTHH:mm:ss".
 *
 * - Converts to specified timezone before extracting datetime.
 * - Defaults to UTC if no timezone specified.
 * - Returns "" for invalid input.
 *
 * @param value UTC datetime string (e.g., "2024-02-29T00:00:00Z")
 * @param options optional: timeZone (IANA)
 * @returns plain datetime string in "YYYY-MM-DDTHH:mm:ss" format or "" on invalid input
 *
 * @example convertUtcToPlainDateTime("2024-02-29T00:00:00Z") // "2024-02-29T00:00:00"
 * @example convertUtcToPlainDateTime("2024-02-29T00:00:00Z", { timeZone: "America/New_York" }) // "2024-02-28T19:00:00"
 * @example convertUtcToPlainDateTime("invalid") // ""
 */
export declare function convertUtcToPlainDateTime(value: string, options?: {
    timeZone?: string;
}): string;