scripts/config_validator.py — standalone validator for all YAML/JSON
config files in the repo.
Checks:
- YAML syntax (pyyaml safe_load)
- JSON syntax (json.loads)
- Duplicate keys in YAML/JSON
- Trailing whitespace
- Tabs in YAML (should use spaces)
- Cron expression validity (if present)
Reports PASS/FAIL per file with line numbers.
Exit 0 if all valid, 1 if any invalid.
