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>

tests/unit/test_database_exception.py

@@ -5,7 +5,7 @@ from pydantic import BaseModel, ValidationError
 from sqlalchemy.exc import IntegrityError, OperationalError
 
 from kilostar.core.postgres_database.database_exception import database_exception
-from kilostar.utils.error import UserNotExistError
+from kilostar.utils.error import UserNotExistError, BusinessError, RetryableError
 
 
 async def test_normal_path_returns_value():
@@ -36,21 +36,22 @@ async def test_validation_error_propagates():
         await boom()
 
 
-async def test_integrity_error_propagates():
+async def test_integrity_error_becomes_business_error():
     @database_exception
     async def boom() -> None:
         raise IntegrityError("stmt", {}, Exception("dup"))
 
-    with pytest.raises(IntegrityError):
+    with pytest.raises(BusinessError) as exc_info:
         await boom()
+    assert exc_info.value.http_status == 409
 
 
-async def test_operational_error_propagates():
+async def test_operational_error_becomes_retryable():
     @database_exception
     async def boom() -> None:
         raise OperationalError("stmt", {}, Exception("conn"))
 
-    with pytest.raises(OperationalError):
+    with pytest.raises(RetryableError):
         await boom()