suggestion: add `--type` flag similar to ripgrep's implementation

[johnsaigle]

It would be great to be able to search only on specific filetypes. I think ripgrep has a great implementation of this that could be a good inspiration.

While ck supports specifying a path or file for searching, filetype filters would be especially helpful.

[runonthespot]

Acknowledged — a ripgrep-style --type rust/--type ts flag is a real ergonomic gap and aligns with the language-recognition work already done in ck-core::Language. Implementation sketch: pre-defined type→glob map (rust = ["*.rs"], ts = ["*.ts", "*.tsx"], etc.) layered on top of the existing --include pipeline. Tracking in our backlog.