feat: 人设模板系统、节点调度标签、pydantic-settings收敛、错误处理增强

新增persona_template表和CRUD API，BaseIndividualModel增加node_affinity和template_origin_id字段，
WorkerCluster支持多集群Ray资源调度，环境变量收敛到pydantic-settings统一校验，
数据库异常转换为结构化BusinessError/RetryableError，系统节点支持custom_system_prompt。

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

kilostar/core/postgres_database/model/individual.py

@@ -43,6 +43,12 @@ class BaseIndividualModel(BaseDataModel):
     owner_id: Mapped[str] = mapped_column(String(64), index=True)
 
     agent_type: Mapped[str] = mapped_column(String(32))
+    node_affinity: Mapped[str] = mapped_column(String(32), nullable=False, default="cpu")
+    template_origin_id: Mapped[Optional[str]] = mapped_column(
+        ForeignKey("persona_template.template_id", ondelete="SET NULL"),
+        nullable=True,
+        index=True,
+    )
 
     __mapper_args__ = {"polymorphic_on": "agent_type", "polymorphic_identity": "base"}