feat(server): 支持 Granian 与 rloop/uvloop/winloop 事件循环

- 新增 scripts/serve.py 启动器：server auto/uvicorn/granian，循环可用性与平台校验（显式不可用直接报错）
- pyproject 增加 granian 可选 extra（granian[reload,rloop,uvloop,winloop]，平台 marker 由 granian 维护）
- tests/test_serve.py 覆盖服务器/循环选择与命令拼装；README 补充启动方式、循环矩阵与多 worker 限制

tests/test_serve.py

@@ -0,0 +1,67 @@
+"""启动器（scripts/serve.py）的循环/服务器选择逻辑测试（不启动真实服务器）。"""
+
+from __future__ import annotations
+
+import sys
+from pathlib import Path
+
+import pytest
+
+sys.path.insert(0, str(Path(__file__).resolve().parent.parent))
+
+from scripts import serve
+
+
+def test_pick_server_auto_prefers_granian(monkeypatch: pytest.MonkeyPatch) -> None:
+    monkeypatch.setattr(serve, "has_module", lambda name: name == "granian")
+    assert serve.pick_server("auto") == "granian"
+
+    monkeypatch.setattr(serve, "has_module", lambda name: False)
+    assert serve.pick_server("auto") == "uvicorn"
+
+
+def test_available_loops_follow_installed_packages(monkeypatch: pytest.MonkeyPatch) -> None:
+    monkeypatch.setattr(serve, "has_module", lambda name: name == "winloop")
+    assert serve.available_loops("granian") == ["auto", "asyncio", "winloop"]
+    assert serve.available_loops("uvicorn") == ["auto", "asyncio"]
+
+    monkeypatch.setattr(serve, "has_module", lambda name: name in ("rloop", "uvloop"))
+    assert serve.available_loops("granian") == ["auto", "asyncio", "rloop", "uvloop"]
+    assert serve.available_loops("uvicorn") == ["auto", "asyncio", "uvloop"]
+
+
+def test_explicit_unavailable_loop_fails_with_hint(monkeypatch: pytest.MonkeyPatch) -> None:
+    monkeypatch.setattr(serve, "has_module", lambda name: False)
+    with pytest.raises(SystemExit) as error:
+        serve.resolve_loop("granian", "rloop")
+    message = str(error.value)
+    assert "rloop" in message and "可用" in message
+
+
+def test_uvicorn_rejects_granian_only_loops() -> None:
+    with pytest.raises(SystemExit):
+        serve.resolve_loop("uvicorn", "winloop")
+    with pytest.raises(SystemExit):
+        serve.resolve_loop("uvicorn", "rloop")
+
+
+def test_uvicorn_auto_and_asyncio_allowed() -> None:
+    assert serve.resolve_loop("uvicorn", "auto") == "auto"
+    assert serve.resolve_loop("uvicorn", "asyncio") == "asyncio"
+
+
+def test_build_command_granian(monkeypatch: pytest.MonkeyPatch) -> None:
+    monkeypatch.setattr(serve, "has_module", lambda name: True)
+    command = serve.build_command("granian", host="0.0.0.0", port=16688, workers=2, loop="winloop", reload=True)
+    assert command[:3] == [sys.executable, "-m", "granian"]
+    assert command[command.index("--loop") + 1] == "winloop"
+    assert command[command.index("--workers") + 1] == "2"
+    assert "--reload" in command
+    assert command[-1] == serve.APP_TARGET
+
+
+def test_build_command_uvicorn() -> None:
+    command = serve.build_command("uvicorn", host="127.0.0.1", port=9000, workers=1, loop="auto", reload=False)
+    assert command[:3] == [sys.executable, "-m", "uvicorn"]
+    assert command[3] == serve.APP_TARGET
+    assert "--reload" not in command