Per-column header bar with size dropdown (small/full), left/right
move arrows, and delete. New "+ Add column" button at the bottom of
the page-columns container. Each action POSTs to a column endpoint
and reloads.
Backend endpoints:
- POST /edit/api/pages/{slug}/columns — add (form: size)
- POST /edit/api/pages/{slug}/columns/{col}/delete
- POST /edit/api/pages/{slug}/columns/{col}/move?dir=left|right
- POST /edit/api/pages/{slug}/columns/{col}/size — set size
All go through configEditor's yaml.Node tree so comments and other
config survive.
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
