fix(rust): explain client-side model files when remote tokenize fails (#4519)

Addresses option 2 of #4440.

tokenize() builds the FTS analyzer on the client. For jieba/* and
lindera/* that needs model files under LANCE_LANGUAGE_MODEL_HOME, and
when they’re missing you only got lance’s raw Invalid directory path:
... error, even though server-side search works.

Now, if a jieba/* or lindera/* tokenizer can’t be built, the error keeps
the original cause and adds that tokenize() runs on the client, which
directory the files need to be in, and that for remote tables they must
match the server’s. I also updated the tokenize docs (Rust, Python, TS,
generated JS docs) to say a mismatch can’t be detected, so tokens may
differ from the server’s index.

Behavior when the files exist is unchanged. Detecting a mismatch needs a
server-side tokenize endpoint (option 1), so I left it out. The hint
isn’t limited to remote tables, since Table::as_native is slated for
removal and the wording fits local tables too.

Tests: Rust test with mocked jieba/default index_details and an empty
model dir, one checking other tokenizer errors don’t get the hint, and
Python sync/async tests.

docs/src/js/classes/Table.md

@@ -1298,7 +1298,11 @@ Specify exactly one of `column` or `indexName`.
 
 Model-backed tokenizers such as `jieba/*` and `lindera/*` are rebuilt in
 the client process from index metadata. For remote tables, this means the
-same tokenizer model files must also exist locally.
+same tokenizer model files must also exist locally (under
+`LANCE_LANGUAGE_MODEL_HOME`) and must match the files the server uses. A
+mismatch cannot be detected: the returned tokens may differ from what the
+server's index produces. If the model files are missing, an error naming
+the tokenizer is raised.
 
 #### Parameters