Refine patrol ET craft movement

[jackandcarter]

Motivation

• Restore patrol ET craft behavior to match the original purple ETs: pass across the screen on a set path, retain detection/shooting, and exhibit jittered lateral motion while optionally biasing toward the player.
• Eliminate the undesired patterned/sinusoidal-only movement and make patrols traverse consistently from spawn side to exit.
• Ensure patrol craft despawn when they exit the camera bounds instead of lingering offscreen.

Description

• Replaced the old startY/direction patrol fields with a patrolDirection vector and set initial velocity to patrolDirection * moveSpeed on enable.
• Added patrolTargetBias and patrolDespawnPadding inspector fields and implemented ResolvePatrolDirection() to derive traversal direction from spawn side.
• Rewrote PatrolMovement() to compute lateral jitter using Perlin noise (combining wanderAmplitude / wanderFrequency and patrolJitterAmplitude / patrolJitterFrequency) and to blend movement toward the target using Vector2.Lerp with patrolTargetBias when the player is within detectionRange.
• Added IsPastPatrolBounds() logic to deactivate (despawn) patrol craft once they pass the view bounds plus patrolDespawnPadding.

Testing

• No automated tests were run for this change.

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Codex Task