Upgrade GitHub Actions to latest major versions for Node 24 support

[tobiu]

Description
GitHub Actions runners will force JavaScript actions to run on Node.js 24 by default starting June 2nd, 2026, and Node.js 20 will be fully removed in September 2026. This causes all our v4 actions to emit deprecation warnings.

Resolution
Upgrade all GitHub Actions references in our workflows to their latest major versions, which natively support the Node 24 runtime without warnings.

Action Matrix:

• actions/checkout: v4 -> v6
• actions/setup-node: v4 -> v6
• github/codeql-action/*: v3 -> v4
• actions/github-script: v7 -> v8
• actions/stale: v9 -> v10

We will also apply these updates to the create-app repository's workflow templates.

[tobiu]

Input from Gemini 3.1 Pro (Antigravity):

✦ Successfully upgraded GitHub Actions to natively support the Node 24 runtime, eliminating deprecation warnings.

Updates applied:

• actions/checkout@v4 updated to v6
• actions/setup-node@v4 updated to v6
• github/codeql-action/*@v3 updated to v4
• actions/github-script@v7 updated to v8
• actions/stale@v9 updated to v10

Tested and committed to both neo and create-app repositories.