feat(quick-260329-ton): replace textContent with innerHTML + renderInlineMarkdown at all AI-text insertion points

- src/app.ts: greeting text now renders inline markdown
- src/ui/screens.ts: letter intro text now renders inline markdown
- src/forest/reward.ts: forest comment now renders inline markdown
- All 3 sites use innerHTML with XSS-safe renderInlineMarkdown

src/app.ts

@@ -1,6 +1,7 @@
 import { speakText } from "./audio/speech";
 import { companions } from "./companion/characters";
 import { getGreeting } from "./companion/companion";
+import { renderInlineMarkdown } from "./utils/markdown";
 import { initRewardScreen, startPreGeneration } from "./forest/reward";
 import { initForestScreen, renderForestScene } from "./forest/scene";
 import { getProgress, openDB, saveProgress } from "./storage/db";
@@ -224,7 +225,7 @@ export async function initApp(): Promise<void> {
 
 			// Fetch greeting async (shows immediately with avatar, text fills in)
 			getGreeting(progress.selectedCharacter, db).then((text) => {
-				textEl.textContent = text;
+				textEl.innerHTML = renderInlineMarkdown(text);
 				speakText(text);
 			});
 		}

src/forest/reward.ts

@@ -22,6 +22,7 @@ import { getRandomFallbackForestComment } from "../companion/fallbacks";
 import type { CompanionType, ForestElement } from "../types";
 import { playRewardSound } from "../audio/sounds";
 import { speakText } from "../audio/speech";
+import { renderInlineMarkdown } from "../utils/markdown";
 
 // --- Element types for random selection ---
 
@@ -204,7 +205,7 @@ export async function initRewardScreen(
 	playRewardSound();
 
 	// 7. Show companion comment + speak it aloud
-	companionTextEl.textContent = comment;
+	companionTextEl.innerHTML = renderInlineMarkdown(comment);
 	speakText(comment);
 
 	// 8. Wire buttons

src/ui/screens.ts

@@ -20,6 +20,7 @@ import { getLevelByNumber } from "../game/levels";
 import { getLetterIntro } from "../companion/companion";
 import { getWordsForLevel } from "../game/words";
 import { playCorrectSound } from "../audio/sounds";
+import { renderInlineMarkdown } from "../utils/markdown";
 
 export function initWelcomeScreen(
 	db: IDBDatabase,
@@ -419,7 +420,7 @@ export function initLessonScreen(
 			if (cancelled) return;
 
 			// Show companion intro text
-			companionText.textContent = introText;
+			companionText.innerHTML = renderInlineMarkdown(introText);
 			companionArea.style.display = "flex";
 
 			// Show the letter