🔄 CI/CD: Pipeline Optimizations & Action Version Pinning

[saint2706]

• Pinned all GitHub Actions to valid latest major versions instead of future fake versions.
• Added actions/checkout@v4 as a prerequisite for actions/dependency-review-action in dependency-review.yml.
• Updated README.md to document the optimizations.
• Verified syntax with actionlint and verified functionality via npm run test and npm run build.

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PR created automatically by Jules for task 992696855369628444 started by @saint2706

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