Import Behavior Designer in an isolated Unity pass

[JOY]

Project: Second Spawn
Area: Unity
Milestone: Vertical Slice
Priority: P1
Size: M
Review Gate: Local Review
Verification: Unity Smoke

Goal

Import Behavior Designer after the controller import/evaluation lane is stable, preserving the rule of one paid package per commit.

Acceptance Criteria

• Asset import happens in an isolated change set.
• Unity console is checked after import.
• A minimal NPC behavior-tree evaluation path is documented.
• No gameplay state mutation is delegated to Behavior Designer without server validation.