Upgrade dependencies and move action runtime to Node 24

[Copilot]

• Investigate all 6 vulnerabilities (undici chain + minimatch/prettier-eslint chain)
• Remove unused prettier-eslint devDependency (fixes minimatch ReDoS vulnerabilities)
• Upgrade @actions/core to v2 (CJS-compatible, pulls in @actions/http-client v3 → undici v6.24.1, fixing 5 undici CVEs)
• Run format, lint, test, build and verify 0 vulnerabilities
• Push and update PR

[CLAassistant]

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1 out of 2 committers have signed the CLA.

✅ Maddimax
❌ Copilot
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