Add Han River flood chapter

src/game/state/campaignState.ts

@@ -120,6 +120,8 @@ export type CampaignStep =
   | 'thirty-eighth-camp'
   | 'thirty-ninth-battle'
   | 'thirty-ninth-camp'
+  | 'fortieth-battle'
+  | 'fortieth-camp'
   | 'hanzhong-king-camp'
   | 'shu-han-foundation-camp';
 
@@ -222,7 +224,8 @@ const campaignBattleSteps: Record<string, { victory: CampaignStep; retry: Campai
   'thirty-sixth-battle-dingjun-vanguard': { victory: 'thirty-sixth-camp', retry: 'thirty-sixth-battle' },
   'thirty-seventh-battle-hanzhong-decisive': { victory: 'thirty-seventh-camp', retry: 'thirty-seventh-battle' },
   'thirty-eighth-battle-jing-defense': { victory: 'thirty-eighth-camp', retry: 'thirty-eighth-battle' },
-  'thirty-ninth-battle-fan-castle-vanguard': { victory: 'thirty-ninth-camp', retry: 'thirty-ninth-battle' }
+  'thirty-ninth-battle-fan-castle-vanguard': { victory: 'thirty-ninth-camp', retry: 'thirty-ninth-battle' },
+  'fortieth-battle-han-river-flood': { victory: 'fortieth-camp', retry: 'fortieth-battle' }
 };
 
 export type CampaignSaveSlotSummary = {