v1.1.0-beta.9

Changed

• Adopt dartastic_opentelemetry_api 1.0.0-rc.1 (constraint
  ^1.0.0-rc.1). No SDK code changes were needed: the SDK never used
  the removed vendor/RUM enums, and it implements the now-abstract
  APIObservableResult interface.
• CI: self-hosted coverage badge built from lcov.info and published to
  the badges branch; Codecov upload removed (uploads had failed since
  branch protection was enabled). The README coverage badge is now live
  data instead of a hardcoded percentage.