refactor(tpv): ClassGenVTable 的 self._mangle_name 统一为 self.Gen.FuncGenBase 显式调用

- 继承链 ClassGenVTable→ClassGenBase（无父类）不含 FuncGenBase，
  5 处 self._mangle_name 沿 MRO 解析不到定义（依赖编译器兜底）
- 统一为 self.Gen.FuncGenBase._mangle_name（对齐项目其他 Mixin 写法）

App/lib/core/Gen/Class/ClassGenVTable.vp

@@ -400,7 +400,7 @@ class ClassGenVTable(ClassGenBase.ClassGenBase):
                 func: llvmlite.Function | t.CPtr = self.Gen.CallGenLeafKit.find_func_global(full_name)
             else:
                 # 当前类方法: 用当前模块 SHA1
-                mangled_name: str = self._mangle_name(trans, full_name)
+                mangled_name: str = self.Gen.FuncGenBase._mangle_name(trans, full_name)
                 func: llvmlite.Function | t.CPtr = self.Gen.CallGenLeafKit.find_func_in_table(
                     trans._funcs, trans._func_count, full_name)
                 # 当前模块表找不到时，回退到全局表
@@ -469,7 +469,7 @@ class ClassGenVTable(ClassGenBase.ClassGenBase):
         if vtable_name_buf is None:
             return 0
         viperlib.snprintf(vtable_name_buf, 128, "%s.vtable", class_name)
-        vtable_mangled: str = self._mangle_name(trans, vtable_name_buf)
+        vtable_mangled: str = self.Gen.FuncGenBase._mangle_name(trans, vtable_name_buf)
 
         # 5. 创建全局变量
         gv: llvmlite.GlobalVariable | t.CPtr = llvmlite.new_global_variable(
@@ -710,7 +710,7 @@ class ClassGenVTable(ClassGenBase.ClassGenBase):
         full_name: str = full_name_buf
 
         # SHA1 命名空间混淆
-        mangled_name: str = self._mangle_name(trans, full_name)
+        mangled_name: str = self.Gen.FuncGenBase._mangle_name(trans, full_name)
 
         # 推断返回类型
         ret_ty: llvmlite.LLVMType | t.CPtr = None
@@ -1152,7 +1152,7 @@ class ClassGenVTable(ClassGenBase.ClassGenBase):
         viperlib.snprintf(full_name_buf, 128, "%s.__before_init__", class_name)
         full_name: str = full_name_buf
 
-        mangled_name: str = self._mangle_name(trans, full_name)
+        mangled_name: str = self.Gen.FuncGenBase._mangle_name(trans, full_name)
 
         # 创建函数
         func: llvmlite.Function | t.CPtr = llvmlite.create_function(
@@ -1229,7 +1229,7 @@ class ClassGenVTable(ClassGenBase.ClassGenBase):
                 if vt_name_buf is not None:
                     viperlib.snprintf(vt_name_buf, 128, "%s.vtable", class_name)
                     vt_full_name: str = vt_name_buf
-                    vt_mangled: str = self._mangle_name(trans, vt_full_name)
+                    vt_mangled: str = self.Gen.FuncGenBase._mangle_name(trans, vt_full_name)
 
                     # GEP 到 __vtable__ 字段（索引 0）
                     vt_slot: llvmlite.Value | t.CPtr = llvmlite.build_gep_struct(