Update 04 Agentic CLM MicroHack model fleet: drop Claude (→ gpt-5.4), switch renewal to gpt-5.4-nano - #412

Node.js 20 is deprecated. The following actions target Node.js 20 but are being forced to run on Node.js 24: actions/checkout@v4, actions/setup-python@v5, tj-actions/changed-files@v46. For more information see: https://github.blog/changelog/2025-09-19-deprecation-of-node-20-on-github-actions-runners/