The .zddc/markdown editors marked every zip member read-only. Add
util.isEditableZipMember (member of a .zddc.zip + session elevated) and let
those through canSave in both editors — so an elevated admin can open a bundle's
policy .zddc (or any member) and save it, which PUTs to the member URL where the
new server-side ServeZipWrite handles the in-place rewrite + in-zip history. The
server (bundle gate + active-admin) is the real authority; this just drives the
editor UX (mount editable, label "config bundle" instead of "read-only (zip)").
Content-archive members stay read-only.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>