fix: 反啃 CPython 标准库全量 (630 文件) 修复函数内 import 漏注册

- _ScopeAnalyzer 缺 visit_Import/visit_ImportFrom → 函数内 import (局部导入) 的名字没注册进作用域
  → aifc.py math/audioop、argparse.py copy/shutil/textwrap 等 763 个 E002 误报消除
- E002 无 jedi 全量: 2332 → 1569 (剩余为 import* 盲区 + 模块级条件导入, jedi 会消大半)
- E004 216 条抽查: enum i(空串真炸)/gzip buf(else 不赋) 为合理保留; functools candidate/dataclasses value 为条件关联盲区
- 新增 2 回归测试 (函数内 import / import from); 304 passed

tests/test_py_detect.py

@@ -580,6 +580,19 @@ class TestDataFlow:
         assert "E002" not in {d["code"] for d in pd.analyze(src, "t.py")}
         assert "E004" not in {d["code"] for d in pd.analyze(src, "t.py")}
 
+    def test_function_local_import_ok(self, pd):
+        """函数内 import 不得误报 E002 (标准库 aifc math / argparse copy 场景)"""
+        src = ("def f(x):\n"
+               "    import math\n"
+               "    return math.frexp(x)\n")
+        assert "E002" not in {d["code"] for d in pd.analyze(src, "t.py")}
+
+    def test_function_local_import_from_ok(self, pd):
+        src = ("def f():\n"
+               "    from math import sqrt\n"
+               "    return sqrt(4)\n")
+        assert "E002" not in {d["code"] for d in pd.analyze(src, "t.py")}
+
     def test_const_iter_always_runs(self, pd):
         """for f in ('a','b','c'): 常量非空 → 循环变量确定 (pydantic v1 host 场景)"""
         src = ("def f(parts):\n"