v0.21.0-beta.1

What's Changed

• docs(release): require editorial GitHub notes by @benvinegar in #946
• fix(extensions): prioritize focused pane editors by @benvinegar in #954
• fix(install): refuse conflicting Hunk installs by @benvinegar in #960
• feat(website): publish prerelease changelogs by @benvinegar in #961
• fix(install): deduplicate binary aliases by @benvinegar in #963
• test(session): characterize lifecycle interleavings by @benvinegar in #949
• fix(session): recover from socket startup failures by @benvinegar in #950
• refactor(session): model startup lifecycle states by @benvinegar in #952
• refactor(session): inject a lifecycle clock by @benvinegar in #953
• fix(session): fence late lifecycle settlements by @benvinegar in #955
• test(session): retain runtime exit fixtures by @benvinegar in #956
• feat(extensions): add pane activation callback by @benvinegar in #965
• chore(release): prepare v0.21.0-beta.1 by @benvinegar in #967

Full Changelog: v0.21.0-beta.0...v0.21.0-beta.1