feat(standalone): 新增单机模式，KILOSTAR_MODE=standalone 时去掉 Ray 依赖

通过 StandaloneProxy 适配层让 .remote() 调用在单机模式下透明降级为
asyncio 协程调用，7 个 Actor 和 workflow task 均可在纯 asyncio 环境运行，
启动快、资源占用低。分布式模式行为完全不变。

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

tests/unit/test_standalone_proxy.py

@@ -0,0 +1,106 @@
+"""standalone_proxy 适配层单元测试。
+
+验证 StandaloneProxy / _MethodProxy / actor_class / remote_task
+在单机模式下的行为是否正确模拟了 Ray Actor Handle 的 .remote() 接口。
+"""
+
+import asyncio
+import pytest
+
+from kilostar.utils import standalone_proxy
+from kilostar.utils.standalone_proxy import StandaloneProxy, _MethodProxy
+
+
+class TestMethodProxy:
+    def test_sync_method(self):
+        def add(a, b):
+            return a + b
+
+        proxy = _MethodProxy(add)
+        result = asyncio.get_event_loop().run_until_complete(proxy.remote(2, 3))
+        assert result == 5
+
+    def test_async_method(self):
+        async def async_add(a, b):
+            return a + b
+
+        proxy = _MethodProxy(async_add)
+        result = asyncio.get_event_loop().run_until_complete(proxy.remote(4, 6))
+        assert result == 10
+
+
+class TestStandaloneProxy:
+    def test_method_call(self):
+        class FakeActor:
+            def greet(self, name):
+                return f"hello {name}"
+
+        proxy = StandaloneProxy(FakeActor())
+        future = proxy.greet.remote("world")
+        result = asyncio.get_event_loop().run_until_complete(future)
+        assert result == "hello world"
+
+    def test_async_method_call(self):
+        class FakeActor:
+            async def compute(self, x):
+                return x * 2
+
+        proxy = StandaloneProxy(FakeActor())
+        future = proxy.compute.remote(7)
+        result = asyncio.get_event_loop().run_until_complete(future)
+        assert result == 14
+
+    def test_attribute_access(self):
+        class FakeActor:
+            def __init__(self):
+                self.name = "test"
+
+        proxy = StandaloneProxy(FakeActor())
+        assert proxy.name == "test"
+
+
+class TestActorClass:
+    def test_standalone_returns_class_unchanged(self, monkeypatch):
+        monkeypatch.setattr(standalone_proxy, "_STANDALONE", True)
+
+        @standalone_proxy.actor_class
+        class MyActor:
+            def do_work(self):
+                return 42
+
+        instance = MyActor()
+        assert instance.do_work() == 42
+
+    def test_standalone_class_is_plain_python(self, monkeypatch):
+        monkeypatch.setattr(standalone_proxy, "_STANDALONE", True)
+
+        @standalone_proxy.actor_class
+        class MyActor:
+            pass
+
+        assert not hasattr(MyActor, "remote")
+        assert not hasattr(MyActor, "options")
+
+
+class TestRemoteTask:
+    def test_sync_task(self, monkeypatch):
+        monkeypatch.setattr(standalone_proxy, "_STANDALONE", True)
+
+        @standalone_proxy.remote_task
+        def multiply(a, b):
+            return a * b
+
+        future = multiply.remote(3, 4)
+        result = asyncio.get_event_loop().run_until_complete(future)
+        assert result == 12
+
+    def test_async_task(self, monkeypatch):
+        monkeypatch.setattr(standalone_proxy, "_STANDALONE", True)
+
+        @standalone_proxy.remote_task
+        async def async_multiply(a, b):
+            return a * b
+
+        future = async_multiply.remote(5, 6)
+        result = asyncio.get_event_loop().run_until_complete(future)
+        assert result == 30