Keep builders coming when DigitalOcean sells out a size or region (#861)

* Keep builders coming when DigitalOcean sells out a droplet size

ric1 sold out of g5-32vcpu-64gb-50gb, and every create came back 422. curl -f
dropped the reason and set -e ended the tick, so builders only appeared when
capacity happened to free up, and the journal showed nothing but "curl: (22)".

Try each of SIZES in turn, logging DigitalOcean's refusal message, and fail
the tick only when every size is refused. Builders now power off however
start.sh exits, so a failed registration is reaped instead of counting as a
booting runner until MAX_AGE_MINUTES. The controller unit pulls the checkout
before each tick, so merged controller fixes reach the box.

* Create builders in any region that has the size in stock

ric1 sold out of g5-32vcpu-128gb-50gb within minutes of the box switching to
it. Builders need nothing from a particular region, so read DigitalOcean's
size catalog once per tick and try each of SIZES in every region it lists in
stock, REGIONS first if set. A refused pair is dropped for the rest of the
tick.

ci/controller-box/omarchy-controller.service

@@ -7,6 +7,9 @@ Wants=network-online.target
 Type=oneshot
 User=controller
 EnvironmentFile=/etc/omarchy-controller.env
+# Run the branch's current controller, not the one cloned when the box was
+# built. As root (the checkout's owner); a failed pull keeps the last one.
+ExecStartPre=-+/usr/bin/git -C /opt/omarchy-pkgs pull --ff-only --quiet
 ExecStart=/opt/omarchy-pkgs/ci/controller.sh
 # The reaper's safety net is time, not state; a hung tick must not hold the lock.
 TimeoutStartSec=240