CLI Output Formatting Enhancements

[toddysm]

Add dedicated output formatting helpers and improve CLI user experience.

Acceptance Criteria

• Create cli/formatting.py with reusable helpers
• Enhance JSON output formatting consistency
• Improve error message formatting
• Add progress indicators for long operations
• Better table formatting for list commands
• Ensure all telemetry goes to stderr (not interfering with piped output)
• Add tests for output formatting

Files to Create/Modify

• src/regshape/cli/formatting.py
• Update CLI modules to use new formatters

References

• specs/architecture.md Section 7: CLI Command Structure