v0.0.12

Added

• The git addon: backs page drafts, publishing, and version history directly onto site's own git repository. A page's git log is its version history.
• Toolkit/Git and Toolkit/GitResult for running git commands and reading results.
• Admin UI for page history and diffs, plus a Publish action in the page editor.

Changed

• Build and Caddy/Dockerfile updates to support the new addon.