security: enforce 0600/0700 file permissions on sensitive files (inspired by openclaw)

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.

cron/jobs.py

@@ -32,10 +32,29 @@ JOBS_FILE = CRON_DIR / "jobs.json"
 OUTPUT_DIR = CRON_DIR / "output"
 
 
+def _secure_dir(path: Path):
+    """Set directory to owner-only access (0700). No-op on Windows."""
+    try:
+        os.chmod(path, 0o700)
+    except (OSError, NotImplementedError):
+        pass  # Windows or other platforms where chmod is not supported
+
+
+def _secure_file(path: Path):
+    """Set file to owner-only read/write (0600). No-op on Windows."""
+    try:
+        if path.exists():
+            os.chmod(path, 0o600)
+    except (OSError, NotImplementedError):
+        pass
+
+
 def ensure_dirs():
-    """Ensure cron directories exist."""
+    """Ensure cron directories exist with secure permissions."""
     CRON_DIR.mkdir(parents=True, exist_ok=True)
     OUTPUT_DIR.mkdir(parents=True, exist_ok=True)
+    _secure_dir(CRON_DIR)
+    _secure_dir(OUTPUT_DIR)
 
 
 # =============================================================================
@@ -223,6 +242,7 @@ def save_jobs(jobs: List[Dict[str, Any]]):
             f.flush()
             os.fsync(f.fileno())
         os.replace(tmp_path, JOBS_FILE)
+        _secure_file(JOBS_FILE)
     except BaseException:
         try:
             os.unlink(tmp_path)
@@ -400,11 +420,13 @@ def save_job_output(job_id: str, output: str):
     ensure_dirs()
     job_output_dir = OUTPUT_DIR / job_id
     job_output_dir.mkdir(parents=True, exist_ok=True)
+    _secure_dir(job_output_dir)
     
     timestamp = _hermes_now().strftime("%Y-%m-%d_%H-%M-%S")
     output_file = job_output_dir / f"{timestamp}.md"
     
     with open(output_file, 'w', encoding='utf-8') as f:
         f.write(output)
+    _secure_file(output_file)
     
     return output_file