docs(classgen): 声明前置注释示例 FileW -> File

FileW 已在 includes/win32/fileio.vp 中删除，示例改用 File.__init__（同样在 self.seek 之前定义）。

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

@@ -497,7 +497,7 @@ novirtual class ClassGenVTable(ClassGenBase.ClassGenBase):
         if oop_has_vt_pre == 1: self._collect_vtable_methods(trans, cd, class_name)
 
         # Declare-before-define: forward-declare every method so lookups no longer depend on
-        # source order (e.g. FileW.__init__ calling self.seek defined later in the class).
+        # source order (e.g. File.__init__ calling self.seek defined later in the class).
         for ci_pd in range(int(cn)):
             stmt_pd: ast.AST* = children.get(ci_pd)
             if stmt_pd is None: continue