Add choice-based events with a resolution modal

Standard/kaos events can now present 2 options instead of a fixed
effect, pausing new event triggers until the player answers. Adds
4 choice events as a first batch; resources keep accruing while a
choice is pending.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

src/main.ts

@@ -1,5 +1,5 @@
 import './style.css';
-import { createState, tick, buyUpgrade, visitLocation, saveState, loadState, clearSave } from './engine.ts';
+import { createState, tick, buyUpgrade, visitLocation, resolveEventChoice, saveState, loadState, clearSave } from './engine.ts';
 import { initUI, renderState } from './ui.ts';
 import { initMap, updateMap } from './map.ts';
 
@@ -22,7 +22,8 @@ function start(): void {
       visitCooldowns = new Map();
       document.getElementById('overlay')!.classList.remove('visible');
       renderState(state);
-    }
+    },
+    (index) => { state = resolveEventChoice(state, index); renderState(state); saveState(state); }
   );
 
   initMap('map', (locationId) => {