Linked zones: shared records kept in step across views

Zones of the same name in different views can be linked. Shared records
are kept in step: a change in one view reaches the others in the same
changeset, as explicit operations, so the diff, permission checks,
history and undo cover every view. Records local to a view override the
shared records of that name and type there; removing the override brings
the shared ones back, and sharing a view's version makes it every view's.
Each zone keeps its own options, serial and file.

Linking existing zones changes no answer: what is the same everywhere
becomes shared, the rest stays local. Unlinking keeps every record, all
local. ACME challenges are written once per link, and --view all changes
a link once. jarl zone link/unlink, zone create --link-with, record
--local/--shared, LINK column, web UI controls, POST /zones/{zone}/link
and /unlink, validation checks linked_*, store migration 11, docs and
e2e.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

cmd/jarl/acme.go

@@ -83,7 +83,7 @@ func acmeZones(c *client.Client, name, view string) ([]acme.Zone, error) {
 	}
 	refs := make([]acme.Zone, len(zones))
 	for i, z := range zones {
-		refs[i] = acme.Zone{Name: z.Name, View: z.View}
+		refs[i] = acme.Zone{Name: z.Name, View: z.View, Link: z.LinkGroup}
 	}
 	out := acme.Zones(name, refs, view)
 	if len(out) == 0 {