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.

hermes_cli/config.py

@@ -46,13 +46,32 @@ def get_project_root() -> Path:
     """Get the project installation directory."""
     return Path(__file__).parent.parent.resolve()
 
+def _secure_dir(path):
+    """Set directory to owner-only access (0700). No-op on Windows."""
+    try:
+        os.chmod(path, 0o700)
+    except (OSError, NotImplementedError):
+        pass
+
+
+def _secure_file(path):
+    """Set file to owner-only read/write (0600). No-op on Windows."""
+    try:
+        if os.path.exists(str(path)):
+            os.chmod(path, 0o600)
+    except (OSError, NotImplementedError):
+        pass
+
+
 def ensure_hermes_home():
-    """Ensure ~/.hermes directory structure exists."""
+    """Ensure ~/.hermes directory structure exists with secure permissions."""
     home = get_hermes_home()
-    (home / "cron").mkdir(parents=True, exist_ok=True)
-    (home / "sessions").mkdir(parents=True, exist_ok=True)
-    (home / "logs").mkdir(parents=True, exist_ok=True)
-    (home / "memories").mkdir(parents=True, exist_ok=True)
+    home.mkdir(parents=True, exist_ok=True)
+    _secure_dir(home)
+    for subdir in ("cron", "sessions", "logs", "memories"):
+        d = home / subdir
+        d.mkdir(parents=True, exist_ok=True)
+        _secure_dir(d)
 
 
 # =============================================================================
@@ -808,6 +827,7 @@ def save_config(config: Dict[str, Any]):
             sections.append("fallback")
         if sections:
             f.write(_COMMENTED_SECTIONS)
+    _secure_file(config_path)
 
 
 def load_env() -> Dict[str, str]:
@@ -860,6 +880,7 @@ def save_env_value(key: str, value: str):
     
     with open(env_path, 'w', **write_kw) as f:
         f.writelines(lines)
+    _secure_file(env_path)
 
 
 def get_env_value(key: str) -> Optional[str]: