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/__tests__/createGatewayEventHandler.test.ts

@@ -26,6 +26,7 @@ const buildCtx = (appended: Msg[]) =>
       colsRef: ref(80),
       newSession: vi.fn(),
       resetSession: vi.fn(),
+      resumeById: vi.fn(),
       setCatalog: vi.fn()
     },
     system: {
@@ -34,6 +35,8 @@ const buildCtx = (appended: Msg[]) =>
     },
     transcript: {
       appendMessage: (msg: Msg) => appended.push(msg),
+      panel: (title: string, sections: any[]) =>
+        appended.push({ kind: 'panel', panelData: { sections, title }, role: 'system', text: '' }),
       setHistoryItems: vi.fn()
     }
   }) as any
@@ -138,4 +141,24 @@ describe('createGatewayEventHandler', () => {
     expect(appended[0]?.thinking).toBe(fromServer)
     expect(appended[0]?.thinkingTokens).toBe(estimateTokensRough(fromServer))
   })
+
+  it('shows setup panel for missing provider startup error', () => {
+    const appended: Msg[] = []
+    const onEvent = createGatewayEventHandler(buildCtx(appended))
+
+    onEvent({
+      payload: {
+        message:
+          'agent init failed: No LLM provider configured. Run `hermes model` to select a provider, or run `hermes setup` for first-time configuration.'
+      },
+      type: 'error'
+    } as any)
+
+    expect(appended).toHaveLength(1)
+    expect(appended[0]).toMatchObject({
+      kind: 'panel',
+      panelData: { title: 'Setup Required' },
+      role: 'system'
+    })
+  })
 })