v1.0.0-rc.1

Promotes 1.0.0-beta.10 to the rc channel — no code changes.

This repo tracks a builtin driver that keeps shipping its own changes independently. Waiting for full parity before calling a release candidate meant an indefinite beta line chasing a moving target. 1.0.0-rc.1 is the checkpoint instead: parity gaps found from here on are tracked as issues/patches on the rc line (rc.2, rc.3, ...), not reasons to hold the channel back.

See CHANGELOG.md for full details.