feat(system):优化后端

1.新增后端测试
2.增加了后端的加密
3.增加了i18n（国际化）

tests/unit/test_utils_get_tool.py

@@ -0,0 +1,44 @@
+"""``utils.get_tool`` 在真实仓库目录上的加载行为。"""
+
+from kilostar.utils import get_tool
+from kilostar.utils.get_tool import (
+    _get_tool_func,
+    del_tool_cache,
+    load_tools_from_list,
+)
+
+
+def setup_function(_func):
+    """每个测试前清空模块级缓存，避免相互影响。"""
+    get_tool._tool_cache.clear()
+
+
+def test_load_existing_tool_via_load_tools_from_list():
+    tools = load_tools_from_list(["file_reader"])
+    assert len(tools) == 1
+    assert tools[0].__name__ == "file_reader"
+
+
+def test_loader_caches_function():
+    f1 = _get_tool_func("file_reader")
+    f2 = _get_tool_func("file_reader")
+    assert f1 is f2
+    assert "file_reader" in get_tool._tool_cache
+
+
+def test_del_tool_cache_removes_entry():
+    _get_tool_func("file_reader")
+    assert "file_reader" in get_tool._tool_cache
+    del_tool_cache("file_reader")
+    assert "file_reader" not in get_tool._tool_cache
+
+
+def test_load_unknown_tool_returns_none_and_keeps_others():
+    tools = load_tools_from_list(["file_reader", "definitely_not_exist"])
+    assert len(tools) == 1
+    assert tools[0].__name__ == "file_reader"
+
+
+def test_load_tools_from_list_handles_none_and_empty():
+    assert load_tools_from_list(None) == []
+    assert load_tools_from_list([]) == []