…deploy needs (#715)

## Summary

Hotfix for the first v7 `test`-branch deployment attempt ([Actions run
#1447 / run id
24796856145](https://github.com/MorpheusAIs/Morpheus-Lumerin-Node/actions/runs/24796856145)).

The previous PR (#714 → #713) introduced a new job sequence:

```
Drain-Morpheus-C-Node → Deploy-to-Morpheus-P-Node → Deploy-to-Morpheus-C-Node
```

On push to `test`, `Deploy-to-Morpheus-P-Node` is correctly **skipped**
(its own `if` restricts it to `main` — no dev P-Node exists). That skip
then propagated onto `Deploy-to-Morpheus-C-Node` through the implicit
`success()` guard that every job has when no explicit `if` tolerates a
skipped dependency. Net effect:

- `Drain-Morpheus-C-Node` ✅ removed the running dev C-Node task from
both NLB target groups.
- `Deploy-to-Morpheus-C-Node` ❌ silently skipped — no new task
registered, no re-register of the existing task.
- Dev C-Node endpoints (`router.dev.mor.org:8082`/`:8545`) stopped
serving traffic until we manually re-registered the old task to the TGs.

## What this PR changes

`.github/workflows/build.yml`, `Deploy-to-Morpheus-C-Node` job only:

### Explicit `if` guard that tolerates the P-Node skip

```yaml
if: |
  !cancelled() &&
  github.repository == 'MorpheusAIs/Morpheus-Lumerin-Node' &&
  needs.GHCR-Build-and-Push.result == 'success' &&
  needs.Drain-Morpheus-C-Node.result == 'success' &&
  (needs.Deploy-to-Morpheus-P-Node.result == 'success' || needs.Deploy-to-Morpheus-P-Node.result == 'skipped') &&
  (
    (github.event_name == 'push' && (github.ref == 'refs/heads/main' || github.ref == 'refs/heads/test')) ||
    (github.event_name == 'workflow_dispatch' && github.event.inputs.build_all_os == 'true' && github.event.inputs.create_deployment == 'true')
  )
```

- Still requires real success from the drain + GHCR jobs.
- Explicitly accepts `success` OR `skipped` for the P-Node dependency.
- `!cancelled()` short-circuits the job if someone cancels the run, so
we don't try to redeploy a half-cancelled sequence.

### Comment rewrite

The previous inline comment claimed skipped jobs are treated as
successful for dependency resolution. That's the opposite of how GitHub
Actions actually behaves — the note is replaced with an accurate
explanation and a reference to this incident so future-us (or other
maintainers) won't step on the same rake.

## What this PR does NOT change

- No change to the drain job or the controlled-traffic C-Node deploy
sequence (register→dereg→hold→rereg→wait).
- No change to the P-Node job or its `if` gating.
- No change to any other workflow or deploy script.

This is a pure guard-correctness fix.

## Test plan

- [x] YAML syntax validated (`yaml.safe_load`).
- [x] Manually walked through `needs` outcomes:
- On push to `test`: P-Node `skipped`, drain + GHCR `success` → C-Node
**runs**. ✅
  - On push to `main`: all three `success` → C-Node **runs**. ✅
- Drain fails → C-Node **skipped** (won't redeploy while the TG state is
ambiguous). ✅
  - GHCR fails → C-Node **skipped**. ✅
- P-Node fails on main (not skipped) → C-Node **skipped** (we want to
bail rather than leave prd with a v-mismatch between providers and the
consumer). ✅
- [ ] Merge to `dev`, promote to `test`, confirm
`Deploy-to-Morpheus-Consumer` actually runs this time and completes the
drain → hold → re-register → /healthcheck cycle end-to-end.
- [ ] Once green on test, cut `test` → `main` for first prd exercise.

## Related

- Previous PR: #714 (dev → test) carrying #713 (initial
drain/sequence/hold).
- Companion IAM + planning doc already applied in `Morpheus-Infra`.

Made with [Cursor](https://cursor.com)