fix(traceback): 通过 .vpi 内容定位 traceback 模块 SHA1

sig_files/source_module_sig_files 的值是 .vpi 路径，basename 不含 traceback；改为读取前 512 字节匹配 'Module: traceback'。

lib/Projectrans/Phase2Translator.py

@@ -2358,13 +2358,21 @@ class Phase2Translator:
         # 直接调用它（不依赖 .ctors/.init_array，避免 MinGW 下 .ctors.65534 不执行）。
         if self.traceback_enabled:
             _tb_sha1: str | None = None
-            for _src_map in (getattr(self, '_shared_source_module_sig_files', {}), self.sig_files):
-                for _k, _p in _src_map.items():
+            for _k, _p in self.sig_files.items():
+                try:
                     if 'traceback' in os.path.basename(_p):
                         _tb_sha1 = _k
                         break
-                if _tb_sha1:
-                    break
+                    if 'Module: traceback' in _ReadTextCached(_p)[:512]:
+                        _tb_sha1 = _k
+                        break
+                except Exception:
+                    continue
+            if _tb_sha1 is None:
+                for _k, _p in getattr(self, '_shared_source_module_sig_files', {}).items():
+                    if 'traceback' in str(_p):
+                        _tb_sha1 = _k
+                        break
             if _tb_sha1 is not None:
                 trans.translator.TracebackInstallSymbol = f'{_tb_sha1}.Install'
         trans.SliceLevel = self.slice_level