Release version 1.1 with bugfixes

Version bump: 1.0 → 1.1

Added:
- CHANGELOG.md - Complete version history and release notes
- TESTING.md - Comprehensive testing checklist
- Version links in README.md

Fixed in v1.1:
- Critical layout issues with fullscreen button
- Red progress bar scrubber positioning
- Better CSS modification approach (setProperty vs cssText)

Documentation:
- Full changelog following Keep a Changelog format
- Testing checklist for all critical UI elements
- Links to changelog and privacy policy in README

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

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