fix(ci): allow check-workflows to be skipped in merge queue skip path (#898)

## Summary

The `all-jobs-complete` gate job was failing with `"check-workflows did
not succeed"` during merge queue runs when only CI files changed
([failed
run](https://github.com/MetaMask/ocap-kernel/actions/runs/23610005457/job/68765093258)).

**Root cause**: When the merge queue determines a PR is already
up-to-date with main (`skip-merge-queue=true`), `check-workflows` is
intentionally skipped. However, the `all-jobs-complete` gate
unconditionally required `check-workflows == success` whenever `HAS_CI`
was true, causing a spurious failure.

**Fix**: Add `check-skip-merge-queue` as a dependency of
`all-jobs-complete` and skip the `check-workflows` requirement when
`skip-merge-queue` is `true` — mirroring the escape hatch that
`all-jobs-pass` already has.

## Changes

- Add `check-skip-merge-queue` to the `needs` list of
`all-jobs-complete` so its outputs are accessible
- Guard the `check-workflows` assertion with a `skip-merge-queue !=
true` condition

## Testing

The fix was verified by tracing the exact failure scenario from the
[merge queue
run](https://github.com/MetaMask/ocap-kernel/actions/runs/23610005457).
The `all-jobs-pass` job already passed in that run via its own escape
hatch, confirming the issue was cosmetic (red X on `all-jobs-complete`)
rather than a merge blocker. This PR makes `all-jobs-complete` itself
behave correctly in this path.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

<!-- CURSOR_SUMMARY -->
---

> [!NOTE]
> **Low Risk**
> Low risk: only adjusts GitHub Actions job gating logic to tolerate an
intentionally skipped `check-workflows` job when `skip-merge-queue` is
true.
> 
> **Overview**
> Prevents false CI failures in merge-queue runs where the PR is already
up to date and `check-workflows` is intentionally skipped.
> 
> `all-jobs-complete` now depends on `check-skip-merge-queue` and only
requires `check-workflows` to have succeeded when `skip-merge-queue` is
not `true`, aligning the final gate behavior with the merge-queue skip
path.
> 
> <sup>Written by [Cursor
Bugbot](https://cursor.com/dashboard?tab=bugbot) for commit
189a693. This will update automatically
on new commits. Configure
[here](https://cursor.com/dashboard?tab=bugbot).</sup>
<!-- /CURSOR_SUMMARY -->

Co-authored-by: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: sirtimid

.github/workflows/main.yml

@@ -232,6 +232,7 @@ jobs:
     if: ${{ always() }}
     needs:
       - detect-changes
+      - check-skip-merge-queue
       - check-workflows
       - analyse-code
       - lint-build-test
@@ -261,8 +262,10 @@ jobs:
           fi
 
           # check-workflows runs for both CI and code changes; require it when either is present
+          # It is intentionally skipped when the merge queue decides to skip (PR already up-to-date)
           if [[ "$HAS_CI" == "true" || "$HAS_CODE" == "true" ]]; then
-            if [[ "${{ needs.check-workflows.result }}" != "success" ]]; then
+            if [[ "${{ needs.check-skip-merge-queue.outputs.skip-merge-queue }}" != "true" \
+                  && "${{ needs.check-workflows.result }}" != "success" ]]; then
               echo "check-workflows did not succeed"
               exit 1
             fi