- Move completed work to docs/archive/planning/ with grouped structure
- Group active projects into dedicated directories (cli-streamlining, aqua-distribution, release-workflow)
- Apply standardized naming conventions (plan.md, status.md, phase-*.md)
- Add status tracking files for each active project
- Update planning README with current status and reorganization instructions
- Add reorganization script for future use

Reorganize planning documentation: group related work and archive completed items

- Add cosign keyless signing to GitHub Actions release workflow
- Bump version to 0.3.1 for testing signed releases
- Create validation script for verifying release signatures
- Add aqua registry configuration for upstream submission
- Create comprehensive testing documentation
- Add local testing script for aqua configuration

This implements Phase 1 and Phase 2 of the aqua distribution plan,
enabling envsense to be distributed via 'mise install aqua:envsense'.

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

feat: implement aqua/mise distribution support