docs: add comprehensive competitor feature analysis to AMELIORATIONS.md (#188)

- Add 40+ new features discovered from Claude Code, Droid, OpenCode, and Codex
- Include detailed Hook Events System analysis (11 event types)
- Document Async Parallel Tasks and Background Agents capabilities
- Add Autonomy Levels System from Droid and Codex
- Include Codex Cloud execution features
- Update comparison tables with new discoveries
- Add new prioritization sections for critical gaps
- Document unique features per competitor
- Include gaps summary showing most requested features across competitors

Co-authored-by: Droid Agent <droid@factory.ai>

Author: echobt