fix: add default value to grep tool glob schema for strict mode compatibility (#422)

* fix: add default value to grep tool glob schema for strict mode compatibility

The grep tool's `glob` field was defined with `.optional().nullable()` but
without `.default()`, causing it to be excluded from the JSON schema
`required` array. This violates OpenAI's strict mode requirement that all
properties must be listed in `required`.

Fixes #401

* Fix grep tool glob schema for strict mode

Added a default value to the grep tool glob schema to ensure compatibility with strict mode.

* Update .changeset/lucky-candles-reply.md

---------

Co-authored-by: Christian Bromann <git@bromann.dev>