Add Chengdu surrender chapter

src/game/state/campaignState.ts

@@ -105,7 +105,9 @@ export type CampaignStep =
   | 'thirty-first-battle'
   | 'thirty-first-camp'
   | 'thirty-second-battle'
-  | 'thirty-second-camp';
+  | 'thirty-second-camp'
+  | 'thirty-third-battle'
+  | 'thirty-third-camp';
 
 export type CampaignUnitProgressSnapshot = {
   unitId: string;
@@ -199,7 +201,8 @@ const campaignBattleSteps: Record<string, { victory: CampaignStep; retry: Campai
   'twenty-ninth-battle-luo-outer-wall': { victory: 'twenty-ninth-camp', retry: 'twenty-ninth-battle' },
   'thirtieth-battle-luofeng-ambush': { victory: 'thirtieth-camp', retry: 'thirtieth-battle' },
   'thirty-first-battle-luo-main-gate': { victory: 'thirty-first-camp', retry: 'thirty-first-battle' },
-  'thirty-second-battle-mianzhu-gate': { victory: 'thirty-second-camp', retry: 'thirty-second-battle' }
+  'thirty-second-battle-mianzhu-gate': { victory: 'thirty-second-camp', retry: 'thirty-second-battle' },
+  'thirty-third-battle-chengdu-surrender': { victory: 'thirty-third-camp', retry: 'thirty-third-battle' }
 };
 
 export type CampaignSaveSlotSummary = {