feat(engine): 实现阵营博弈机制

- FactionData 新增 threshold 和 skill 字段
- 修改能量累积逻辑：power 跨 tick 累积
- 阈值改为 10，达到后触发阵营技能
- festival 提升情绪，panic 降低情绪

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

engine-python/app/models.py

@@ -47,6 +47,8 @@ class Stance(BaseModel):
 class FactionData(BaseModel):
     """单个派系的数据"""
     power: int = 0
+    threshold: int = 10
+    skill: str = ""
     members: List[str] = Field(default_factory=list)