v2.0.0-rc.9

Changes since v2.0.0-rc.8

• fix(main): quit when the hidden countdown overlay is the last window left
• docs(testing): log the v2.0.0-rc.8 e2e pass and fix the export peak check
• docs(testing): state the output level the rc.8 loudness export used
• fix(preview): hand out no native view while the view for a new source is created

Full Changelog: v2.0.0-rc.8...v2.0.0-rc.9