Release version 1.1.21 - Add multilingual support for Swiss locales

Added translations for Swiss German (formal and informal), Swiss French,
and Swiss Italian locales to support multilingual e-commerce in Switzerland.

New Features:
- Added de_CH (Swiss German - formal "Sie") translation
- Added de_DE_informal (Informal German - "du") translation
- Added fr_CH (Swiss French) translation
- Added it_CH (Swiss Italian) translation

Technical Changes:
- Created 4 new .po translation source files
- Compiled all .po files to .mo format for runtime use
- Updated version to 1.1.21 in plugin header and constant
- Updated composer.json version to 1.1.21
- Swiss locales use CHF currency formatting (e.g., "CHF 50.-")
- German informal translations use "du/dein" instead of "Sie/Ihr"

Documentation:
- Updated CHANGELOG.md with v1.1.21 release notes
- Updated CLAUDE.md with current version and translation status
- Marked roadmap item as completed in CLAUDE.md

Release Package:
- Created wc-tier-and-package-prices-1.1.21.zip (404 KB)
- Generated MD5 checksum: 16813b3ed0d1001d5f60194d61d36fc2
- Generated SHA256 checksum: e0063852a9ac23b1fd994471a2829f9dcbe26316f00ddee2d00f77c7c6a47c8f

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

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