Release v1.3.64

Two features reach a tag at once, because the host-takeover branch was cut from
the operating-mode branch and carries all of it.

The operating mode: a test and a live setting for the whole installation, every
credential with a test slot beside its live one, a stored key that says which
mode it belongs to, and a Stripe catalogue that refuses to act on objects from
the other account.

The host takeover: the bootstrap script that turns a machine in a rescue system
into a finished Proxmox host, the archive that serves it, the one-time enrolment
code, and the six-step guide in the console under Hosts and Add host. None of
the script's steps has been accepted on real hardware yet — every hardware step
in its plan is still unticked, and the console work is what this release makes
visible.

Also in here, found while writing the takeover: host names were being built from
the CUSTOMER zone. RegisterHostDns says clupilot.com in its own docblock, and on
this installation a host was actually called fsn-01.node.clupilot.cloud. There
is a platform_zone now and the step uses it.

2017 tests pass.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

VERSION

@@ -1 +1 @@
-1.3.63
+1.3.64