fix(template): Make "Finished Build and Publish" gate reflect real build outcome

The `finished` job is the single required status check for the build
workflow. It had no `if:` clause, so a failed dependency caused GitHub to
*skip* it rather than fail it - and branch protection treats a skipped
required check as passing. A broken build (e.g. a failed
publish-index-manifest) therefore became mergeable.

Two fixes:

- Add `if: always()` so the gate always runs and reports a real
  success/failure conclusion.
- List every leaf job directly in `needs` and fail the gate on any
  `failure`/`cancelled` result. Previously publish-index-manifest was only
  a transitive dependency (via openshift-preflight-check), so its failure
  would not surface in `needs.*.result`. `skipped` is tolerated, since jobs
  skip legitimately on merge_group events, forks, and when detect-changes
  finds no relevant changes.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Author: lfrancke

template/.github/workflows/build.yaml.j2

@@ -372,13 +372,41 @@ jobs:
     # WARNING: Do not change the name unless you will also be changing the
     # Required Checks (in branch protections) in GitHub settings.
     name: Finished Build and Publish
+    # Run even when a dependency failed, was skipped or cancelled, so that this
+    # gate reflects the real outcome. Without `always()` a failed dependency
+    # would *skip* this job, and GitHub treats a skipped required check as
+    # passing - making a broken build mergeable.
+    if: always()
+    # List every leaf job directly. A transitive failure (e.g. a failed
+    # publish-index-manifest that skips openshift-preflight-check) does not
+    # surface as `failure` in `needs.*.result` unless the failing job is a
+    # direct dependency.
     needs:
+      - detect-changes
       - cargo-udeps
-      - openshift-preflight-check
+      - build-container-image
+      - publish-index-manifest
+      - provenance-oci
+      - provenance-quay
       - publish-helm-chart
+      - openshift-preflight-check
     runs-on: ubuntu-latest
     steps:
-      - run: echo "We are done here"
+      # Skipped dependencies are fine (jobs skip legitimately on merge_group
+      # events, forks, or when detect-changes finds no relevant changes). Only
+      # a failure or cancellation must fail this gate.
+      - name: Fail on any failed or cancelled dependency
+        env:
+          RESULTS: ${{ join(needs.*.result, ' ') }}
+        run: |
+          echo "Dependency results: $RESULTS"
+          for result in $RESULTS; do
+            if [ "$result" = "failure" ] || [ "$result" = "cancelled" ]; then
+              echo "::error::A required job did not succeed (result: $result)"
+              exit 1
+            fi
+          done
+          echo "We are done here"
 
   notify:
     name: Failure Notification