Refactor: Extract shared markdown builders for rules generation strategies

[mkczarkowski]

Problem

The Single and Multi-file rules generation strategies contained significant code duplication:

• Both strategies duplicated project header setup logic
• Empty-state messaging was repeated in both files
• Library iteration and markdown generation logic was implemented separately
• This duplication made it harder to maintain consistency and add new features

Solution

Extracted common scaffolding into a shared markdown-builders module that provides reusable utilities:

New Shared Builders

• createProjectMarkdown - Generates consistent project headers
• createEmptyStateMarkdown - Returns standardized empty state message
• getProjectMetadata - Provides standard project file metadata
• renderLibrarySection - Renders library markdown with configurable headers
• iterateLayersStacksLibraries - Unified iteration logic over layer/stack/library structure
• createLibraryFileMetadata - Generates file metadata for multi-file output

Key Benefits

✅ Single source of truth - All markdown generation logic now lives in one place
✅ Guaranteed consistency - Both strategies use the same builders, ensuring uniform formatting
✅ Easier maintenance - Changes to formatting only need to be made once
✅ Reduced complexity - Strategies are now simpler and focus on their core responsibility
✅ Better testability - Shared builders can be tested independently
✅ Future-proof - Adding new strategies is now much simpler

Changes Made

1. Created new src/services/rules-builder/markdown-builders/index.ts module
2. Refactored SingleFileRulesStrategy to use shared builders
3. Refactored MultiFileRulesStrategy to use shared builders
4. Removed duplicated code from both strategies

Testing

• ✅ All existing unit tests pass
• ✅ Linting passes with no errors
• ✅ No functional changes - output remains identical

🤖 Generated with Claude Code

[github-actions]

✅ All checks have passed successfully!

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

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