fix(cli): let gateway use config port by default

Respect config.gateway.port when --port is omitted, while keeping CLI flags as the highest-precedence override.

nanobot/cli/commands.py

@@ -290,7 +290,7 @@ def _load_runtime_config(config: str | None = None, workspace: str | None = None
 
 @app.command()
 def gateway(
-    port: int = typer.Option(18790, "--port", "-p", help="Gateway port"),
+    port: int | None = typer.Option(None, "--port", "-p", help="Gateway port"),
     workspace: str | None = typer.Option(None, "--workspace", "-w", help="Workspace directory"),
     verbose: bool = typer.Option(False, "--verbose", "-v", help="Verbose output"),
     config: str | None = typer.Option(None, "--config", "-c", help="Path to config file"),
@@ -310,6 +310,7 @@ def gateway(
         logging.basicConfig(level=logging.DEBUG)
 
     config = _load_runtime_config(config, workspace)
+    port = port if port is not None else config.gateway.port
 
     console.print(f"{__logo__} Starting nanobot gateway on port {port}...")
     sync_workspace_templates(config.workspace_path)