feat: add shell style guide, git commit standard, and project-specific rules for pg_index_pilot
- Add comprehensive shell style guide based on Google's bash style guide
- Add project-specific rules structure with pg-index-pilot example
- Update README with documentation for project-specific rules
The shell guide covers:
- Bash-only approach with security guidelines
- Formatting, naming conventions, and best practices
- Reference to Google's style guide for consistency
Project-specific rules allow:
- Repository-specific rule inclusion
- Organized by project identifier matching
- Extensible for future projects