v0.9.0

Changelog

• 30762ac: Add CHANGELOG backfilled from v0.1.0 to v0.7.0 (@s-johri)
• b32093c: Warn on unknown config keys; document frozen config.toml schema (@s-johri)
• 85bb461: Warn instead of swallowing a malformed config on launch (@s-johri)
• 6f2e0d5: Add vhs demo tape and finalize v0.9.0 docs (@s-johri)
• 174969c: Add generated demo GIF (@s-johri)