refactor(text): unify Chinese conversion on Rust (#6481)

tests/test_jieba_utils.py

@@ -1,4 +1,4 @@
-from app.foundation.text import cut
+from app.foundation.text import convert, cut
 
 
 def test_cut_accepts_hmm_argument():
@@ -19,3 +19,8 @@ def test_cut_preserves_full_mode_contract():
         "长江大桥",
         "大桥",
     ]
+
+
+def test_convert_uses_rust_mediawiki_contract():
+    """标准与 free-threaded 运行时应共享同一中文转换语义。"""
+    assert convert("后台", "zh-hant") == "後台"