Integrate rebuilt battle scene into Fight

[Rick-1091]

Summary

• Integrates the rebuilt boss battle into Assets/_Game/Scenes/Fight.unity and keeps Fight_RebuiltBossBattle.unity aligned.
• Connects the existing project character artwork/animations to the rebuilt battle controller.
• Updates player health/animation handling and adds an editor validation smoke test for the integrated fight scenes.

Validation

• Unity 2022.3.62f3 compile/resource validation passed locally.
• Battle smoke test passed locally: grounded spawn, jump/landing, idle animation, and active shield.

Notes

• This PR only targets the integration branch from Rick's fork. It does not directly modify the upstream main branch until reviewed and merged.