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

ui-tui/src/app/useMainApp.ts

@@ -1,4 +1,4 @@
-import { type ScrollBoxHandle, useApp, useHasSelection, useSelection, useStdout } from '@hermes/ink'
+import { useApp, useHasSelection, useSelection, useStdout, type ScrollBoxHandle } from '@hermes/ink'
 import { useStore } from '@nanostores/react'
 import { useCallback, useEffect, useMemo, useRef, useState } from 'react'
 
@@ -270,6 +270,7 @@ export function useMainApp(gw: GatewayClient) {
     colsRef,
     composerActions,
     gw,
+    panel,
     rpc,
     setHistoryItems,
     setLastUserMsg,
@@ -413,10 +414,11 @@ export function useMainApp(gw: GatewayClient) {
           colsRef,
           newSession: session.newSession,
           resetSession: session.resetSession,
+          resumeById: session.resumeById,
           setCatalog
         },
         system: { bellOnComplete, stdout, sys },
-        transcript: { appendMessage, setHistoryItems }
+        transcript: { appendMessage, panel, setHistoryItems }
       }),
     [
       appendMessage,