release: 0.2.0-alpha

Journal redesign, live views, unified buffer architecture, block
mirroring, read-only buffers, per-pane cursors, and 20+ bug fixes.

See CHANGELOG.md for full details.

chore: add git-cliff config and generated CHANGELOG.md

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>