fix: CI pipeline Node.js 20 deprecation, Codecov input, img lint errors

Agent-Logs-Url: https://github.com/christianlouis/InboxConverge/sessions/6bbc5b0e-ece1-4bed-8bf7-20e1e7027948

Co-authored-by: christianlouis <361235+christianlouis@users.noreply.github.com>

.github/workflows/ci.yml

@@ -15,6 +15,7 @@ env:
   GHCR_REGISTRY: ghcr.io
   PRIVATE_REGISTRY: registry.cklnet.com
   K8S_STATE_REPO: christianlouis/k8s-cluster-state
+  FORCE_JAVASCRIPT_ACTIONS_TO_NODE24: true
 
 jobs:
   # ── Phase 1: Lint ──────────────────────────────────────────────────────
@@ -125,7 +126,7 @@ jobs:
       - name: Upload coverage to Codecov
         uses: codecov/codecov-action@v5
         with:
-          file: ./backend/coverage.xml
+          files: ./backend/coverage.xml
           flags: unittests
           name: codecov-umbrella
           fail_ci_if_error: false