feat(fts): add UTF-8 support for tokenizer and token filters via utf8proc (#515)

python/zvec/model/param/__init__.pyi

@@ -714,15 +714,19 @@ class FtsIndexParam(IndexParam):
 
     Attributes:
         type (IndexType): Always ``IndexType.FTS``.
-        tokenizer_name (str): Name of the tokenizer (e.g., "standard", "jieba").
+        tokenizer_name (str): Name of the tokenizer (one of "standard", "jieba",
+            "whitespace").
             Default is "standard".
         filters (list[str]): List of token filter names applied after tokenization.
-            Default is ["lowercase"].
+            Supported filters are "lowercase" and "ascii_folding". Default is
+            ["lowercase"].
         extra_params (str): Additional parameters passed to the tokenizer.
             Default is "".
 
     Examples:
-        >>> params = FtsIndexParam(tokenizer_name="jieba", filters=["lowercase"])
+        >>> params = FtsIndexParam(
+        ...     tokenizer_name="jieba", filters=["lowercase", "ascii_folding"]
+        ... )
         >>> print(params.tokenizer_name)
         jieba
     """
@@ -739,7 +743,8 @@ class FtsIndexParam(IndexParam):
 
         Args:
             tokenizer_name (str, optional): Tokenizer name. Defaults to "standard".
-            filters (list[str], optional): Token filter names. Defaults to ["lowercase"].
+            filters (list[str], optional): Token filter names. Supports
+                "lowercase" and "ascii_folding". Defaults to ["lowercase"].
             extra_params (str, optional): Extra tokenizer parameters. Defaults to "".
         """