v6.1.0-rc.1 retired the legacy update endpoints before a replacement
existed, so the UI's Update button failed with an internal-jargon 410
(issue #1564). This lands the replacement end to end: update_container
is a typed agentexec operation with its own strict codec, durable
receipts, and a request digest bound to the image digest the plan
observed; the unified agent bridges execution to the Docker module's
existing pull/backup/recreate/verify/rollback implementation (which now
reports rollback attempt and outcome); and the container action
executor plans, dispatches, and reconciles the operation with declared
backup/rollback compensation truth. Containers advertise an
admin-approval update capability while an image update with a stated
current digest is detected. The legacy endpoints stay retired but
return actionable copy.
Proven live against a Colima daemon: single-container update, the
issue-1564 shared-network-namespace update, and the full UI journey
(Update button, governed review, approve, run) all completed with the
namespace preserved and the backup retained.
