refactor(standalone): 收敛 _STANDALONE 判断到 standalone_proxy 单一来源

各模块不再各自读 os.environ，统一从 standalone_proxy._STANDALONE 导入，
环境变量只在一处决定模式，减少散落的重复逻辑。

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

kilostar/api/__init__.py

@@ -20,7 +20,8 @@ from fastapi.middleware.cors import CORSMiddleware
 from fastapi.responses import FileResponse, JSONResponse
 from fastapi.staticfiles import StaticFiles
 
-_STANDALONE = os.environ.get("KILOSTAR_MODE", "distributed") == "standalone"
+from kilostar.utils.standalone_proxy import _STANDALONE
+
 if not _STANDALONE:
     from ray import serve
 

kilostar/core/global_state_machine/global_state_machine.py

@@ -12,11 +12,9 @@
 #  See the License for the specific language governing permissions and
 #  limitations under the License.
 
-import os
 from typing import Any, Dict, List, Optional, Tuple
-from kilostar.utils.standalone_proxy import actor_class
+from kilostar.utils.standalone_proxy import actor_class, _STANDALONE
 
-_STANDALONE = os.environ.get("KILOSTAR_MODE", "distributed") == "standalone"
 if not _STANDALONE:
     import ray
 

kilostar/core/global_state_machine/gsm_snapshot.py

@@ -30,11 +30,11 @@ GSM 仍然是 source of truth + 写入串行化器，但读路径解耦：
 from __future__ import annotations
 
 import asyncio
-import os
 from dataclasses import dataclass, field
 from typing import Any, Callable, Dict, List, Optional, Tuple
 
-_STANDALONE = os.environ.get("KILOSTAR_MODE", "distributed") == "standalone"
+from kilostar.utils.standalone_proxy import _STANDALONE
+
 if not _STANDALONE:
     import ray
 

kilostar/utils/ray_hook.py

@@ -11,12 +11,11 @@
 #  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 #  See the License for the specific language governing permissions and
 #  limitations under the License.
-import os
 import time
 from functools import lru_cache
 from typing import Any, Dict
 
-_STANDALONE = os.environ.get("KILOSTAR_MODE", "distributed") == "standalone"
+from kilostar.utils.standalone_proxy import _STANDALONE
 
 if not _STANDALONE:
     import ray

kilostar/worker_cluster/worker_cluster.py

@@ -12,14 +12,12 @@
 #  See the License for the specific language governing permissions and
 #  limitations under the License.
 
-import os
 import time
 import asyncio
 from collections import OrderedDict
-from kilostar.utils.standalone_proxy import actor_class
+from kilostar.utils.standalone_proxy import actor_class, _STANDALONE
 from kilostar.utils.ray_hook import ray_actor_hook
 
-_STANDALONE = os.environ.get("KILOSTAR_MODE", "distributed") == "standalone"
 if _STANDALONE:
     from asyncio import Queue
 else: