🔄 CI/CD: Pin GitHub Actions to correct major versions to fix pipeline failures

[saint2706]

This PR updates all GitHub Actions referenced across the .github/workflows configurations to their correct, currently supported major versions.

Context:
The workflows were failing because they contained non-existent, future versions of various GitHub actions (such as actions/checkout@v6, actions/github-script@v8, etc.).

Changes:

• Downgraded actions/checkout to @v4
• Downgraded actions/upload-artifact to @v4
• Downgraded actions/github-script to @v7
• Downgraded actions/cache to @v4
• Downgraded actions/upload-pages-artifact to @v3
• Downgraded actions/deploy-pages to @v4
• Downgraded github/codeql-action/* to @v3

Verification:

• Validated modifications using git diff.
• Verified all project checks passed locally (npm run lint, npm run test:coverage, npm run validate-content, npm run build).

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PR created automatically by Jules for task 16320393491928611160 started by @saint2706

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