chore: seed 5.0.0-beta.0 release

History was squashed into the initial commit of this repo, so release-please
has no user-facing commits to build a changelog from. This forces the first
beta release of the 5.x line off the current dev tip.

Release-As: 5.0.0-beta.0
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

Author: riglar