feat: add level time limits with countdown timer

- Add `timeLimit` configuration to levels 1-4
- Implement countdown timer that starts when throttle is pressed
- Display remaining time in HUD, turning red when under 10s
- Add 'time-up' failure condition and message in LevelFailedScene

src/data/levels/level01.js

@@ -4,6 +4,7 @@ export default {
   name: "GoFundMe",
   description: "Get the Money!",
   kidsAboard: 4,
+  timeLimit: 60,
   startPosition: { x: 200, y: 700 },
   startAngle: 0,
   terrain: [

src/data/levels/level02.js

@@ -15,6 +15,7 @@ export default {
   name: 'Big Air',
   description: 'Clear the gap and land level, or the kids pay for it.',
   kidsAboard: 3,
+  timeLimit: 20,
   startPosition: { x: 100 * WORLD_SCALE, y: 350 * WORLD_SCALE },
   startAngle: 0,
   terrain: [{ points: runway }, { points: landing }],

src/data/levels/level03.js

@@ -32,6 +32,7 @@ export default {
   name: 'Tight Squeeze',
   description: 'A steep valley and a long run of sharp bumps - lean early, lean often.',
   kidsAboard: 4,
+  timeLimit: 20,
   startPosition: { x: 100 * WORLD_SCALE, y: 350 * WORLD_SCALE },
   startAngle: 0,
   terrain: [{ points: buildPoints() }],

src/data/levels/level04.js

@@ -4,6 +4,7 @@ export default {
   name: "Mega Drop",
   description: "",
   kidsAboard: 5,
+  timeLimit: 76,
   startPosition: { x: 200, y: 700 },
   startAngle: 0,
   terrain: [

src/scenes/LevelFailedScene.js

@@ -5,6 +5,7 @@ import { createButton } from '../util/ui.js';
 const REASON_TEXT = {
   'all-kids-lost': 'Every kid got thrown off the bus!',
   'bus-fell': 'The bus fell into the gap!',
+  'time-up': 'Ran out of time before reaching the finish line!',
 };
 
 export default class LevelFailedScene extends Phaser.Scene {

src/scenes/PlayScene.js

@@ -21,6 +21,8 @@ export default class PlayScene extends Phaser.Scene {
     this.levelId = data.levelId;
     this.level = getLevelById(this.levelId);
     this._levelEnded = false;
+    this._timerStarted = false;
+    this._timeRemaining = this.level.timeLimit;
   }
 
   create() {
@@ -62,11 +64,14 @@ export default class PlayScene extends Phaser.Scene {
     if (this._levelEnded) return;
 
     const intent = this.inputController.getIntent();
+    if (!this._timerStarted && intent.throttle > 0) this._timerStarted = true;
+
     this.bus.applyIntent(intent);
     this.engineSound.update();
     this.finishLine.update(time);
     this.cameraRig.update();
     this._updateParallax();
+    this._updateTimer(delta);
     this._checkBusFell();
     this._checkAllKidsLost();
 
@@ -168,6 +173,28 @@ export default class PlayScene extends Phaser.Scene {
     }
   }
 
+  // Counts down only once the player has actually hit the gas (throttle >
+  // 0) for the first time - sitting idle at the start line costs nothing,
+  // matching "the clock is your speedrun, not your reaction time" framing.
+  _updateTimer(delta) {
+    if (!this._timerStarted || this._timeRemaining <= 0) return;
+
+    this._timeRemaining = Math.max(0, this._timeRemaining - delta / 1000);
+    this.timerText.setText(this._formatTime(this._timeRemaining));
+    this.timerText.setColor(this._timeRemaining <= 10 ? '#c0392b' : '#1a1f29');
+
+    if (this._timeRemaining <= 0) {
+      this.events.emit('level-failed', { reason: 'time-up' });
+    }
+  }
+
+  _formatTime(seconds) {
+    const whole = Math.max(0, Math.ceil(seconds));
+    const m = Math.floor(whole / 60);
+    const s = whole % 60;
+    return `${m}:${String(s).padStart(2, '0')}`;
+  }
+
   _buildGoal() {
     const goal = this.level.goal;
     this.goalBody = this.matter.add.rectangle(goal.x, goal.y, goal.width, goal.height, {
@@ -196,6 +223,14 @@ export default class PlayScene extends Phaser.Scene {
       backgroundColor: '#ffffffaa',
     }).setScrollFactor(0).setDepth(10);
 
+    this.timerText = this.add.text(GAME_WIDTH - startX, y, this._formatTime(this._timeRemaining), {
+      fontFamily: 'monospace',
+      fontSize: `${32 * WORLD_SCALE}px`,
+      fontStyle: 'bold',
+      color: '#1a1f29',
+      backgroundColor: '#ffffffaa',
+    }).setOrigin(1, 0).setScrollFactor(0).setDepth(10);
+
     if (DEBUG) {
       this.debugText = this.add.text(startX, y + 52 * WORLD_SCALE, 'g-force: 0.00', {
         fontFamily: 'monospace',