fix(tui): first-run setup preflight + actionable no-provider panel

- tui_gateway: new `setup.status` RPC that reuses CLI's
  `_has_any_provider_configured()`, so the TUI can ask the same question
  the CLI bootstrap asks before launching a session
- useSessionLifecycle: preflight `setup.status` before both `newSession`
  and `resumeById`, and render a clear "Setup Required" panel when no
  provider is configured instead of booting a session that immediately
  fails with `agent init failed`
- createGatewayEventHandler: drop duplicate startup resume logic in
  favor of the preflighted `resumeById`, and special-case the
  no-provider agent-init error as a last-mile fallback to the same
  setup panel
- add regression tests for both paths

tests/test_tui_gateway_server.py

@@ -129,6 +129,14 @@ def test_enable_gateway_prompts_sets_gateway_env(monkeypatch):
     assert server.os.environ["HERMES_INTERACTIVE"] == "1"
 
 
+def test_setup_status_reports_provider_config(monkeypatch):
+    monkeypatch.setattr("hermes_cli.main._has_any_provider_configured", lambda: False)
+
+    resp = server.handle_request({"id": "1", "method": "setup.status", "params": {}})
+
+    assert resp["result"]["provider_configured"] is False
+
+
 def test_config_set_reasoning_updates_live_session_and_agent(tmp_path, monkeypatch):
     monkeypatch.setattr(server, "_hermes_home", tmp_path)
     agent = types.SimpleNamespace(reasoning_config=None)