chore(deps): remove explicit platform-specific rollup dependency

Remove @rollup/rollup-darwin-arm64 from optionalDependencies. Bundlers
like Rollup automatically manage platform-specific native bindings via
their own optionalDependencies, which prevents CI failures on Linux
environments.

This resolves EBADPLATFORM errors in CI/CD where darwin-arm64 packages
are not compatible with Linux platforms.

🤖 Generated with Claude Code

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Author: aledlie