feat: replace --start/--end with --days param on backup command

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

src/order_bak/cli.py

@@ -1,4 +1,4 @@
-from datetime import timezone
+from datetime import datetime, timedelta, timezone
 from pathlib import Path
 
 import click
@@ -31,11 +31,14 @@ def scan(ctx, count):
 
 
 @main.command()
-@click.option("--start", required=True, type=click.DateTime(formats=["%Y-%m-%d"]), help="Start date (UTC, inclusive)")
-@click.option("--end", required=True, type=click.DateTime(formats=["%Y-%m-%d"]), help="End date (UTC, exclusive)")
+@click.option("--days", required=True, type=int, help="Backup orders older than N days (min 1)")
 @click.option("--scan", "scan_path", default=None, type=click.Path(), help="Path to scan CSV (default: latest in scan_dir)")
 @click.pass_context
-def backup(ctx, start, end, scan_path):
+def backup(ctx, days, scan_path):
+    if days < 1:
+        click.echo("Error: --days must be at least 1")
+        raise SystemExit(1)
+
     cfg = load_config(ctx.obj["config_path"])
     from order_bak.backup import backup_orders
 
@@ -48,18 +51,14 @@ def backup(ctx, start, end, scan_path):
             raise SystemExit(1)
         scan_file = scan_files[-1]
 
-    start_utc = start.replace(tzinfo=timezone.utc)
-    end_utc = end.replace(tzinfo=timezone.utc)
-
-    if start_utc >= end_utc:
-        click.echo("Error: --start must be before --end")
-        raise SystemExit(1)
+    today_utc = datetime.now(timezone.utc).replace(hour=0, minute=0, second=0, microsecond=0)
+    cutoff = today_utc - timedelta(days=days)
 
+    click.echo(f"Backing up orders before {cutoff.strftime('%Y-%m-%d')} UTC")
     backup_orders(
         scan_path=scan_file,
         backup_dir=Path("./backups"),
-        start=start_utc,
-        end=end_utc,
+        cutoff=cutoff,
     )