test workflow: apt-packages (e.g. ffmpeg for media tests) and several contracts-src directories

ddiff --git a/.github/workflows/test.yml b/.github/workflows/test.yml
iindex 3d5c6e7..97de63c 100644
---- a/.github/workflows/test.yml
++++ b/.github/workflows/test.yml
@@@ -12,12 +12,14 @@ name: test
  #       uses: OpenVibers/OpenVibe.Shared/.github/workflows/security.yml@<sha>
  #
  # Steps, in order:
++#   packages     apt-get install of `apt-packages`, when set (e.g. ffmpeg for media tests)
  #   install      `install` (default npm ci) with the npm cache
  #   syntax       node --check on every .js/.cjs/.mjs file under `syntax-dirs` (default: server
  #                scripts), node_modules excluded; a directory that does not exist is skipped
  #   test         `test` (default npm test)
--#   contracts    openvibe-contracts-check --service <contracts-service> --src <contracts-src>, when
--#                contracts-service is set: the code's capability and event use against the release
++#   contracts    openvibe-contracts-check --service <contracts-service> --src <dir> for each directory
++#                in contracts-src, when contracts-service is set: the code's capability and event use
++#                against the release
  #   extra        `extra`, when set: any further commands, one per line (e.g. a budget check)
  on:
    workflow_call:
@@@ -30,6 +32,10 @@ on:
          description: Directory holding package.json.
          type: string
          default: .
++      apt-packages:
++        description: Space-separated Ubuntu packages to install first ("" skips).
++        type: string
++        default: ''
        install:
          description: Install command.
          type: string
@@@ -47,7 +53,7 @@ on:
          type: string
          default: ''
        contracts-src:
--        description: Source directory openvibe-contracts-check scans.
++        description: Space-separated source directories openvibe-contracts-check scans.
          type: string
          default: server
        extra:
@@@ -71,6 +77,11 @@ jobs:
            node-version: ${{ inputs.node-version }}
            cache: npm
            cache-dependency-path: ${{ inputs.working-directory }}/package-lock.json
++      - name: packages
++        if: ${{ inputs.apt-packages != '' }}
++        env:
++          PKGS: ${{ inputs.apt-packages }}
++        run: sudo apt-get update -qq && sudo apt-get install -y -qq --no-install-recommends $PKGS
        - name: install
          run: ${{ inputs.install }}
        - name: syntax
@@@ -92,7 +103,12 @@ jobs:
          run: ${{ inputs.test }}
        - name: contracts
          if: ${{ inputs.contracts-service != '' }}
--        run: npx openvibe-contracts-check --service "${{ inputs.contracts-service }}" --src "${{ inputs.contracts-src }}"
++        env:
++          SERVICE: ${{ inputs.contracts-service }}
++          SRC: ${{ inputs.contracts-src }}
++        run: |
++          args=(); for d in $SRC; do args+=(--src "$d"); done
++          npx openvibe-contracts-check --service "$SERVICE" "${args[@]}"
        - name: extra
          if: ${{ inputs.extra != '' }}
          run: ${{ inputs.extra }}