chore: scaffold Dino Land with canvas base game loop

js/game.js

@@ -0,0 +1,28 @@
+const canvas = document.getElementById('game');
+const ctx = canvas.getContext('2d');
+
+const state = {
+  running: true,
+  lastTs: performance.now()
+};
+
+function drawBackground() {
+  ctx.fillStyle = '#88d34f';
+  ctx.fillRect(0, 420, canvas.width, 120);
+}
+
+function tick(ts) {
+  if (!state.running) return;
+  const dt = Math.min((ts - state.lastTs) / 1000, 0.05);
+  state.lastTs = ts;
+
+  ctx.clearRect(0, 0, canvas.width, canvas.height);
+  drawBackground();
+
+  requestAnimationFrame(tick);
+}
+
+requestAnimationFrame((ts) => {
+  state.lastTs = ts;
+  requestAnimationFrame(tick);
+});