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/ui.ts

@@ -2,7 +2,7 @@ import type { State } from './engine.ts';
 import { UPGRADES } from './upgrades.ts';
 import { VERSION, CHANGELOG } from './data/version.ts';
 
-export function initUI(app: HTMLElement, onUpgrade: (id: string) => void, onRestart: () => void): void {
+export function initUI(app: HTMLElement, onUpgrade: (id: string) => void, onRestart: () => void, onEventChoice: (index: number) => void): void {
   app.innerHTML = `
     <div id="header">
       <div class="brand">DJUPET</div>
@@ -120,10 +120,24 @@ export function initUI(app: HTMLElement, onUpgrade: (id: string) => void, onRest
       <div class="overlay-body" id="overlay-body"></div>
       <button class="overlay-btn" id="overlay-btn">Börja om</button>
     </div>
+
+    <div id="event-modal" class="help-modal">
+      <div class="help-modal-inner" id="event-modal-inner">
+        <div class="help-modal-body">
+          <div class="event-modal-text" id="event-modal-text"></div>
+          <div class="event-modal-choices" id="event-modal-choices"></div>
+        </div>
+      </div>
+    </div>
   `;
 
   document.getElementById('overlay-btn')!.addEventListener('click', onRestart);
 
+  document.getElementById('event-modal-choices')!.addEventListener('click', e => {
+    const btn = (e.target as Element).closest('[data-choice]') as HTMLElement | null;
+    if (btn?.dataset['choice'] !== undefined) onEventChoice(Number(btn.dataset['choice']));
+  });
+
   const helpModal = document.getElementById('help-modal')!;
   const helpInner = document.getElementById('help-modal-inner')!;
   document.getElementById('help-btn')!.addEventListener('click', () => helpModal.classList.toggle('visible'));
@@ -198,6 +212,31 @@ export function renderState(state: State): void {
 
   // Overlay
   if (state.phase !== 'playing') showOverlay(state);
+
+  // Event choice modal
+  renderEventModal(state);
+}
+
+let lastPendingEventId: string | null = null;
+
+function renderEventModal(state: State): void {
+  const modal = document.getElementById('event-modal')!;
+  const pending = state.pendingEvent;
+  const id = pending?.event.id ?? null;
+  if (id === lastPendingEventId) return;
+  lastPendingEventId = id;
+
+  if (!pending) {
+    modal.classList.remove('visible');
+    return;
+  }
+
+  document.getElementById('event-modal-text')!.textContent = pending.event.text;
+  const choices = document.getElementById('event-modal-choices')!;
+  choices.innerHTML = (pending.event.choices ?? []).map((c, i) =>
+    `<button class="upgrade-btn" data-choice="${i}"><span class="up-name">${c.text}</span></button>`
+  ).join('');
+  modal.classList.add('visible');
 }
 
 let lastUpgradeKey = '';