ci: update artifact upload actions to use standard upload-artifact action

.gitea/actions/local-ci-build/action.yml

@@ -282,7 +282,7 @@ runs:
     # ── Upload build artifacts on success ─────────────────────────────────────
     - name: Upload artifacts
       if: success() && inputs.skip-artifact != 'true'
-      uses: https://gitea.emulab.it/Simone/local-ci-cd-system/.gitea/actions/local-ci-build@main
+      uses: actions/upload-artifact@v4
       with:
         name: ${{ steps.invoke-ci.outputs.artifact-name }}
         path: ${{ steps.invoke-ci.outputs.artifact-path }}\
@@ -292,7 +292,7 @@ runs:
     # ── Upload diagnostic logs on failure ─────────────────────────────────────
     - name: Upload diagnostic logs on failure
       if: failure()
-      uses: https://gitea.emulab.it/Simone/local-ci-cd-system/.gitea/actions/local-ci-build@main
+      uses: actions/upload-artifact@v4
       with:
         name: build-logs-${{ github.sha }}
         path: ${{ steps.invoke-ci.outputs.artifact-path }}\*.log