Core movement and world motion

[JakeyMarsh1]

As a player, I want smooth up/down movement and a scrolling world so that it feels like a horizontal runner.

Acceptance Criteria:

• ArrowUp/Down and W/S adjust player Y at fixed speed and clamp to screen bounds.​
• Constant forward motion is visible (camera or scrolling background) with a single tunable speed.​
• No jitter at bounds; motion appears smooth at target FPS.​

Tasks:

• Player component with update loop and clamp-to-viewport.​
• Input listeners (Arrow keys, W/S).​
• Implement camera scroll or tileSprite background; expose speed constant.​
• Dev test for responsiveness and smoothness.