Add dependency review gate

[sameer2191]

Summary

• add a pinned GitHub Dependency Review workflow for pull requests
• fail risky dependency additions on moderate-or-higher vulnerabilities across runtime and development scopes
• document the dependency-review gate in README, SECURITY, benchmark, research, and validation evidence

Validation

• Verified dependency-review-action v5.0.0 SHA: a1d282b36b6f3519aa1f3fc636f609c47dddb294 via GitHub API
• ruby -e 'require "yaml"; Dir[".github/workflows/*.yml"].each { |file| YAML.load_file(file); puts file }'
• npm run verify
• npm run package:check
• npm pack --dry-run --json
• npm run audit:prod
• git diff --check
• rg -n -i "recruiter|career|resume|proof|impress|job apply|jobs apply|linkedin" README.md docs SECURITY.md .github package.json src tests scripts install.sh install.ps1 llms.txt CONTRIBUTING.md