feat(review): 新增确定性检查前置与结论结构化内核

- checks.py：确定性检查（find_zero_length / find_duplicate_entities 传 window
  + 纯 Python 派生空文字、未闭合多段线）。问题带 source=deterministic，handle 来自
  工具/数据本身，不依赖 LLM 回忆
- findings.py：解析 LLM 的 JSON 结论 + handle 交叉校验（引用未知 handle 时保留问题、
  剥掉 handle、verified=False）+ findings 装配
- config.py：新增 DETERMINISTIC_CHECKS / VALIDATE_HANDLES / CHECK_UNCLOSED_POLYLINES
  开关与 ZERO_LENGTH_TOLERANCE / DUP_TOLERANCE / DUP_GROUP_LIMIT

实机验证：find_zero_length / find_duplicate_entities 的 window 参数在基座上生效
（schema 未声明，C++ 侧 parseCommonQuery 实际支持）。

tests/test_config.py

@@ -27,6 +27,26 @@ def test_read_env_missing_returns_empty(monkeypatch):
     assert config._read_env("CAD_TEST_DEFINITELY_MISSING_XYZ") == ""
 
 
+def test_read_bool_defaults_when_unset(monkeypatch):
+    monkeypatch.delenv("CAD_TEST_BOOL_UNSET", raising=False)
+    assert config._read_bool("CAD_TEST_BOOL_UNSET", True) is True
+    assert config._read_bool("CAD_TEST_BOOL_UNSET", False) is False
+
+
+def test_read_bool_empty_string_uses_default(monkeypatch):
+    monkeypatch.setenv("CAD_TEST_BOOL_EMPTY", "  ")
+    assert config._read_bool("CAD_TEST_BOOL_EMPTY", True) is True
+
+
+def test_read_bool_truthy_and_falsy(monkeypatch):
+    for raw in ("1", "true", "TRUE", "Yes", "on"):
+        monkeypatch.setenv("CAD_TEST_BOOL", raw)
+        assert config._read_bool("CAD_TEST_BOOL", False) is True
+    for raw in ("0", "false", "no", "off", "nope"):
+        monkeypatch.setenv("CAD_TEST_BOOL", raw)
+        assert config._read_bool("CAD_TEST_BOOL", True) is False
+
+
 def test_has_api_key_reflects_module_value(monkeypatch):
     monkeypatch.setattr(config, "API_KEY", "")
     assert config.has_api_key() is False
@@ -50,6 +70,22 @@ def test_constants_have_expected_types():
     assert isinstance(config.CHECKLIST_PATH, type(config.PROJECT_ROOT))
 
 
+def test_credibility_constants_have_expected_types():
+    assert isinstance(config.DETERMINISTIC_CHECKS, bool)
+    assert isinstance(config.VALIDATE_HANDLES, bool)
+    assert isinstance(config.CHECK_UNCLOSED_POLYLINES, bool)
+    assert isinstance(config.ZERO_LENGTH_TOLERANCE, float)
+    assert isinstance(config.DUP_TOLERANCE, float)
+    assert isinstance(config.DUP_GROUP_LIMIT, int)
+
+
+def test_credibility_defaults_are_on():
+    # 默认开启，保证默认拿到可信度收益
+    assert config.DETERMINISTIC_CHECKS is True
+    assert config.VALIDATE_HANDLES is True
+    assert config.CHECK_UNCLOSED_POLYLINES is True
+
+
 def test_checklist_path_resolves_relative_to_root():
     assert config.CHECKLIST_PATH.name == "review_checklist.json"
     assert config.CHECKLIST_PATH.parent == config.PROJECT_ROOT