다중 시간봉 전략 설정기능 추가

frontend/src/utils/strategyStartNodes.ts

@@ -0,0 +1,41 @@
+import { generateNodeId } from './strategyTypes';
+
+export const START_NODE_ID = '__strategy_start__';
+export const DEFAULT_START_CANDLE = '1m';
+
+export const STRATEGY_CANDLE_TYPES = [
+  '1m', '3m', '5m', '15m', '30m', '1h', '4h', '1d',
+] as const;
+
+export type StrategyCandleType = (typeof STRATEGY_CANDLE_TYPES)[number];
+
+export type StartNodeMeta = {
+  candleType: string;
+};
+
+/** START가 2개 이상일 때 분기 간 결합 연산 */
+export type StartCombineOp = 'AND' | 'OR';
+
+export const DEFAULT_START_COMBINE_OP: StartCombineOp = 'AND';
+
+export function isStartNodeId(id: string): boolean {
+  return id === START_NODE_ID || id.startsWith('__strategy_start_');
+}
+
+export function createStartNodeId(): string {
+  return `__strategy_start_${generateNodeId()}__`;
+}
+
+export function defaultStartMeta(): Record<string, StartNodeMeta> {
+  return { [START_NODE_ID]: { candleType: DEFAULT_START_CANDLE } };
+}
+
+export function normalizeStartCandleType(value: string | undefined | null): string {
+  const raw = (value ?? DEFAULT_START_CANDLE).trim().toLowerCase();
+  if (raw === '1d') return '1d';
+  return (STRATEGY_CANDLE_TYPES as readonly string[]).includes(raw) ? raw : DEFAULT_START_CANDLE;
+}
+
+export function formatStartCandleLabel(candleType: string): string {
+  return normalizeStartCandleType(candleType);
+}