fix(deploy): resolve the proxy probe's named port so the migration can start

[yetone]

What breaks

The production deploy has not been able to run its schema migration. Run 34529081984 failed with deploy-release: job_failed after the Job hit DeadlineExceeded at 600s, which reads as "the catch-up migration is too big". It is not — the migration never started at all.

The Deployment's cloud-sql-proxy declares:

ports: [{containerPort: 9090, name: pg-health}]
startupProbe: {httpGet: {path: /readiness, port: pg-health}}

buildMigrationJob copies that probe onto the Job's sidecar, but cleanContainerForJob strips ports. The name then has nothing to resolve against, and kubelet says so:

Warning  Unhealthy  pod/cumora-migrate-...  Startup probe errored and resulted in
unknown state: strconv.Atoi: parsing "pg-health": invalid syntax

A native sidecar whose startup probe never passes never reports started, so the migrate container is never launched. Observed live in cumora-migrate-e11b024-34531956583: proxy ready=false started=false, proxy logs "The proxy has started successfully and is ready for new connections!", migrate container PodInitializing nine minutes in. The Job then burns its whole deadline and its pod is reaped, so there are no logs to reveal that nothing ran.

The fix

Resolve a named httpGet/tcpSocket port against the source container's port list at the point where the probe is copied, while that list is still in hand. When the name cannot be resolved, return null so the caller keeps its existing numeric default — shipping a probe that can never pass is strictly worse than using our own.

The Job's containers still declare no ports; only the probe target changes.

Tests

The fixture's proxy had neither ports nor a startupProbe, so the suite only ever exercised the numeric fallback path — which is exactly why this never showed up before production. Two cases added, both verified to fail on main:

not ok 4 - a proxy probe on a named port is resolved to its number, ...
not ok 5 - an unresolvable named probe port falls back to a probe that can actually pass