Add html-email-formatter package

[avigoldman]

Summary

• Migrated email-pretty package from parcel repo to Customer.io monorepo as @ciolabs/html-email-formatter
• Converted from ranges-apply to magic-string for string manipulation
• Updated dependencies to use workspace packages for conditional comment handling
• Converted tests from snapshot-based to explicit assertions
• Fixed ESLint violations (unicorn/prefer-string-slice)

Changes

New Package: @ciolabs/html-email-formatter

Created new package with monorepo structure:

• package.json - Package configuration with workspace dependencies
• src/index.ts - Main email formatter implementation
• src/index.test.ts - Test suite with explicit assertions
• tsconfig.json - TypeScript configuration
• tsup.config.ts - Build configuration

Key Implementation Changes

• String manipulation: Replaced ranges-apply with magic-string for better performance and workspace consistency
• Dependencies: Updated to use workspace packages:
  • @ciolabs/html-find-conditional-comments (was find-conditional-comments)
  • @ciolabs/html-preserve-comment-whitespace (was preserve-comment-whitespace)
• Function name: Renamed from emailPretty to emailFormatter for clarity
• Logging: Removed internal logger dependency (was @internal/logger)
• Code style: Fixed ESLint violations for string method preferences

Functionality

The package provides HTML email formatting with special handling for:

• Conditional comments (MSO/Outlook compatibility)
• Whitespace preservation within comments
• Proper indentation alignment of open/close tags
• Full HTML formatting with configurable options

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Latest commit: 917776e

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