Enforce owner-only permissions on files and directories that contain
secrets or sensitive data:
- cron/jobs.py: jobs.json (0600), cron dirs (0700), job output files (0600)
- hermes_cli/config.py: config.yaml (0600), .env (0600), ~/.hermes/* dirs (0700)
- cli.py: config.yaml via save_config_value (0600)
All chmod calls use try/except for Windows compatibility.
Includes _secure_file() and _secure_dir() helpers with graceful fallback.
8 new tests verify permissions on all file types.
Inspired by openclaw v2026.3.7 file permission enforcement.
