Make SPACE_RULE optional in JSON schema grammar generation
Change SPACE_RULE from `| " " | "\n"{1,2} [ \t]{0,20}` to `( " " | "\n"{1,2} [ \t]{0,20} )?`
to make whitespace optional where this rule is used.
🤖 Generated with [Claude Code](https://claude.com/claude-code)
Co-Authored-By: Claude <noreply@anthropic.com>
