fix: write the checkout on disk

.agents/skills/checkout/SKILL.md

@@ -19,6 +19,8 @@ Build my weekly checkout covering Sunday through today.
    - **Gitea**: Launch one subagent to run `~/bin/gitea-activity -s START -e END` and extract commits, PRs (opened/merged/approved), and repositories worked on
 4. **Query dataindex directly** for the full week as backup to ensure nothing is missed
 
+**Output location**: Write the checkout to `checkouts/checkout_$(date +%Y-%m-%d).md` (ISO date without hour)
+
 **Build the checkout with this structure:**
 
 ```