Clear and concise description of the problem

Would like an option to disable tsdown:builtin-css with a simple boolean option. Currently the only way to achieve this is to mutate the plugins array.

Suggested solution

Add {css: false} to options.

Alternative

No response

Additional context

No response

Validations

• Follow our Code of Conduct
• Read the Contributing Guide.
• Check that there isn't already an issue that request the same feature to avoid creating a duplicate.