feat(03-03): render forest elements from IndexedDB in grid

- renderForestScene() loads elements from IDB and renders as images
- Object URLs tracked and revoked on re-render to prevent memory leaks
- Random +-10-20px offset for natural element placement
- New element animation class applied via newElementId parameter
- Integrated into initForestScreen alongside renderLevelMap

src/forest/scene.ts

@@ -1,6 +1,55 @@
 import type { Progress, LevelStatus } from "../types";
 import { levels } from "../game/levels";
-import { getProgress } from "../storage/db";
+import { getProgress, getForestElements } from "../storage/db";
+
+let activeObjectUrls: string[] = [];
+
+export async function renderForestScene(
+	db: IDBDatabase,
+	newElementId?: number,
+): Promise<void> {
+	const grid = document.getElementById("forest-grid");
+	if (!grid) return;
+
+	// Revoke old object URLs to prevent memory leaks
+	for (const url of activeObjectUrls) {
+		URL.revokeObjectURL(url);
+	}
+	activeObjectUrls = [];
+
+	const elements = await getForestElements(db);
+	grid.innerHTML = "";
+
+	// Render up to 12 elements (4x3 grid)
+	const maxSlots = 12;
+	const toRender = elements.slice(0, maxSlots);
+
+	for (const element of toRender) {
+		const slot = document.createElement("div");
+		slot.className = "forest__element";
+
+		const img = document.createElement("img");
+		const objectUrl = URL.createObjectURL(element.imageBlob);
+		activeObjectUrls.push(objectUrl);
+		img.src = objectUrl;
+		img.alt = element.description;
+
+		// Random offset +-10-20px for natural placement
+		const offsetX =
+			(Math.random() > 0.5 ? 1 : -1) * (10 + Math.random() * 10);
+		const offsetY =
+			(Math.random() > 0.5 ? 1 : -1) * (10 + Math.random() * 10);
+		img.style.transform = `translate(${Math.round(offsetX)}px, ${Math.round(offsetY)}px)`;
+
+		// Animate newly added element
+		if (element.id === newElementId) {
+			slot.classList.add("forest__element--new");
+		}
+
+		slot.appendChild(img);
+		grid.appendChild(slot);
+	}
+}
 
 export function getLevelStatus(
 	levelNum: number,
@@ -62,6 +111,7 @@ export async function initForestScreen(
 	if (!progress) return;
 
 	renderLevelMap(mapContainer, progress, onStartLesson);
+	await renderForestScene(db);
 
 	const allComplete = levels.every((l) =>
 		progress.completedLevels.includes(l.level),