Update GitHub Actions runtimes

[thossullivan]

What changed

• updates all shipped consumer examples to the current Node 24 action majors:
  • actions/checkout@v7
  • actions/setup-node@v7
  • actions/upload-artifact@v7
  • actions/download-artifact@v8
• moves the bot template's tool runtime from EOL Node 20 to the project's supported Node 22 baseline
• disables setup-node's automatic package-manager cache in every consumer and repository job
• adds zero-dependency package-contract assertions for action majors, runtime, and cache policy

Why

The live hosted consumer UAT passed, but GitHub annotated the copied bot workflow because its @v4 actions still used the deprecated Node 20 action runtime. The repository's executable workflows had already moved forward; the README, examples, and packaged bot template had drifted.

Node 20 itself reached EOL on April 30, 2026. Disabling automatic npm-cache discovery also keeps a consumer repository's package metadata from silently changing the behavior of the read-only eval or write-capable publish jobs.

Validation

• npm test
• node bot/test/package.mjs
• YAML parsing for all changed workflows/templates
• repository-wide scan confirms no stale action majors or Node 20 workflow targets
• package remains dependency-free