Fix ladder latch behaviour

[AAMIRAU]

This PR updates the ladder behaviour in Below The Surface.

Previously, the player had to press an extra input before latching onto a ladder.

Changes made:

• Player now automatically latches onto a ladder when making contact.
• Prevented the ClimbState from being recreated while already climbing.
• Added a short hold-DOWN timer.
• A quick DOWN press still allows normal downward climbing.
• Holding DOWN for around 500 ms unlatches the player and switches to JumpFallState.
• The timer resets when DOWN is released.

Testing:

• Auto-latching when jumping into a ladder.
• Staying latched with no input.
• Climbing upward.
• Short DOWN press for normal downward movement.
• Holding DOWN to unlatch and fall.

All tested behaviours worked as expected.

[kottochii]

Repository is not in use, please create PRs in https://github.com/thoth-tech/arcade-games.