**Rust workers exit after 30 consecutive claim_next failures.**
Both `prop-grid-rs` and `hrrr-point-worker` ran a `while` loop that
slept 10s and retried forever on `claim_next` errors. If Postgres
went unreachable, pods would stay alive but useless — no circuit
breaker, no liveness probe, just an infinite stream of error logs.
Now we increment a consecutive-failure counter and exit with an
error once it hits 30 (~5 minutes of DB unavailability). k8s
restart policy then cycles the pod, which both triggers an
operator alert and gives us a fresh sqlx pool on the way back up.
A successful claim (Some or None) resets the counter so one
flaky query doesn't poison it.
**BeaconMonitorsTest: drop the Process.sleep(1100).** The test
relied on wall-clock gaps to disambiguate `inserted_at` values on
the `:utc_datetime` (second-precision) timestamps — one full
second of sleep per run, and on shared CI it could still flake
when both inserts landed in the same second. Replaced with an
explicit `Repo.update_all` that back-dates the first row by one
second. 1.1s faster, deterministic.
Users can now register beacon monitors on the settings page. Each
monitor gets a unique random token the remote program will use to
authenticate its reports. Name is the only user-supplied field for
now; more will be added as the monitor protocol is defined.
Also adds :gen_smtp to deps. Swoosh's SMTP adapter depends on
:mimemail which lives in that package, and production was 500'ing
when trying to send confirmation emails without it.
