Fix /etc/micronas dir permissions: 750 root:www-data so Apache can traverse

700 blocked www-data from entering the dir even though the passwd file
had correct group permissions.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

app.py

@@ -49,7 +49,8 @@ def _verify_password(password):
 
 def _save_credentials(user, password):
     h = _hash_password(password)
-    os.makedirs(_CONF_DIR, exist_ok=True)
+    os.makedirs(_CONF_DIR, mode=0o750, exist_ok=True)
+    subprocess.run(['chown', 'root:www-data', _CONF_DIR], capture_output=True)
     Path(_ENV_FILE).write_text(f'MICRONAS_USER={user}\nMICRONAS_PASS_HASH={h}\n')
     os.chmod(_ENV_FILE, 0o600)
     _creds['user']  = user