Add compressed size estimation and better error handling:
- Show both uncompressed (for safety) and estimated compressed size
- Handle calculation failure gracefully with clear message
- Estimate compression ratio at ~90% (divide by 10)
- Add conditional check to prevent arithmetic errors
Example output:
- Espace requis (non compressé + 20%): 1.7GiB
- Espace estimé après compression: 170MiB
- Archive finale: 55MiB (actual result)
This helps users understand why the required space seems larger
than the final backup size (compression factor).
🤖 Generated with [Claude Code](https://claude.com/claude-code)
Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>
fb2a3585d4