Clear and concise description of the problem

Currently, it's challenging to create type-safe configuration generators because:

1. Critical option types aren't exported
2. Arrayable wrapping forces unnecessary array handling when creating single configs

Suggested solution

1. Export key option types

export type {} from 'rolldown'

// src/index.ts
export type {
  // region re-export from options, and maybe more
  Format,
  Sourcemap,
  // endregion
  Options,
  ResolvedOptions,
  UserConfig,
  UserConfigFn,
} from './options'

export {
  ExternalOption,
  InputOption,
  InputOptions,
  InternalModuleFormat,
  MinifyOptions,
  ModuleFormat,
  OutputOptions,
} from 'rolldown'

2. Make UserConfig non-arrayable

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.