Update CHANGELOG.md for Phase 2

[raincamp]

Description

Document all Phase 2 changes in CHANGELOG.md following Keep a Changelog format.

Acceptance Criteria

• Add [1.1.0-alpha] - YYYY-MM-DD section
• List all new features under ### Added
• List any changes under ### Changed
• List any fixes under ### Fixed
• Include all 27 Phase 2 features
• Follow existing CHANGELOG format
• Clear, user-friendly descriptions
• Link to relevant issues/PRs if applicable

Files to Modify

• CHANGELOG.md

Dependencies

• Should be done after all Phase 2 features are complete

Sprint

Sprint 5: Accessibility & Polish

Priority

High