fix: restore agent.close() cleanup and correct /restart category

- Add agent.close() call to _finalize_shutdown_agents() to prevent
  zombie processes (terminal sandboxes, browser daemons, httpx clients)
- Global cleanup (process_registry, environments, browsers) preserved
  in _stop_impl() during conflict resolution
- Move /restart CommandDef from 'Info' to 'Session' category to match
  /stop and /status

hermes_cli/commands.py

@@ -140,7 +140,7 @@ COMMAND_REGISTRY: list[CommandDef] = [
     CommandDef("commands", "Browse all commands and skills (paginated)", "Info",
                gateway_only=True, args_hint="[page]"),
     CommandDef("help", "Show available commands", "Info"),
-    CommandDef("restart", "Gracefully restart the gateway after draining active runs", "Info",
+    CommandDef("restart", "Gracefully restart the gateway after draining active runs", "Session",
                gateway_only=True),
     CommandDef("usage", "Show token usage and rate limits for the current session", "Info"),
     CommandDef("insights", "Show usage insights and analytics", "Info",