fix: 불가침 제의 기한을 20년으로 제한

packages/logic/src/diplomacy/index.ts

@@ -149,3 +149,4 @@ export const processDiplomacyMonth = (
 export * from './frontState.js';
 export * from './instantResponse.js';
 export * from './messageValidity.js';
+export * from './treatyTerm.js';

packages/logic/src/diplomacy/treatyTerm.ts

@@ -0,0 +1,5 @@
+export const NON_AGGRESSION_MIN_TERM_MONTHS = 6;
+export const NON_AGGRESSION_MAX_END_YEAR_OFFSET = 20;
+
+export const resolveNonAggressionMaxEndYear = (currentYear: number): number =>
+    currentYear + NON_AGGRESSION_MAX_END_YEAR_OFFSET;