refactor: extract shared markdown builders from rules generation strategies

[mkczarkowski]

Problem

The SingleFileRulesStrategy and MultiFileRulesStrategy classes contained significant code duplication for generating markdown content. Both strategies independently implemented:

• Project header creation
• Empty state messaging
• Library content formatting
• Section structure rendering

This duplication made the codebase harder to maintain and increased the risk of inconsistencies when making changes.

Solution

Extracted common markdown generation logic into a shared utility module rulesMarkdownBuilders.ts containing:

Shared Functions

• createProjectMarkdown() - Generates consistent project headers
• createEmptyStateMarkdown() - Creates empty state messages
• generateLibraryContent() - Formats individual library rules
• renderLibrarySection() - Renders complete library sections with headers
• generateLibrarySections() - Builds all library sections organized by layer/stack
• PROJECT_FILE_CONFIG - Centralizes default file configuration

Changes Made

• Refactored SingleFileRulesStrategy to use shared utilities (removed ~40 lines)
• Refactored MultiFileRulesStrategy to use shared utilities (removed ~20 lines)
• Created new shared module with well-documented, reusable functions

Benefits

✅ Eliminates ~60 lines of duplicate code
✅ Ensures consistent formatting across all strategies
✅ Simplifies adding new strategies - just import and use shared functions
✅ Makes copy changes easier - update in one place, affects all strategies
✅ Improves maintainability - single source of truth for markdown generation
✅ Better testability - shared functions can be unit tested independently

Testing

All existing tests pass without modification, confirming this is a pure refactoring with no behavior changes.

npm run test ✅
npm run lint:check ✅

🤖 Generated with Claude Code

[github-actions]

✅ All checks have passed successfully!

• Lint: ✅
• Unit Tests: ✅
• E2E Tests: ✅

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