Fix duplicate output in disk-usage script with awk

Replace grep-based parsing with awk to properly capture header and data
lines without duplicates.

Changes:
- Use awk to capture header line (Original/Compressed/Deduplicated size)
- Print header followed by matching "All archives" line with sizes
- Exit immediately after first match to prevent duplicates

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

scripts/disk-usage.sh

@@ -27,7 +27,7 @@ echo ""
 
 # Statistiques du repository Borg
 echo -e "${YELLOW}Espace utilisé par le repository Borg (toutes archives):${NC}"
-borgmatic info 2>/dev/null | grep -B1 "All archives" | grep -E "Original size|All archives" | head -2
+borgmatic info 2>/dev/null | awk '/Original size.*Compressed size.*Deduplicated size/{header=$0; next} /All archives:.*[GT]B/{if(header) print header; print; exit}'
 
 echo ""