docs: add comprehensive ESLint rules analysis and implementation guides

- ESLINT_RECOMMENDATIONS.md: detailed analysis of patterns and rules
- ESLINT_PR_PROPOSALS.md: 10 actionable PR proposals with configs
- ESLINT_QUICKSTART.md: quick implementation guide with templates

Co-authored-by: kraenhansen <1243959+kraenhansen@users.noreply.github.com>

Author: Copilot