opentui(phase3): launcher integration — HERMES_TUI_ENGINE dual-engine

hermes --tui launches the native OpenTUI engine (Bun) when
HERMES_TUI_ENGINE=opentui (env) or display.tui_engine=opentui (config);
Ink stays the default and the shipping path is untouched.

- _resolve_tui_engine() (env > config > ink); refuses opentui on
  Windows/Termux (no Bun) -> falls back to ink with a notice.
- _make_opentui_argv() -> [bun, src/entry.real.tsx] (no build step).
- _bun_bin() with HERMES_BUN override.
- Branch at top of _make_tui_argv BEFORE _ensure_tui_node (Bun-only host
  must not bootstrap Node).
- Gate _launch_tui NODE_OPTIONS/--max-old-space-size on engine==ink (Bun
  is JSC; the V8 flag errors/ignores).

Verified end-to-end via tmux: real hermes --tui -> Bun -> OpenTUI ->
real Python gateway streamed a real reply. No-flag default still ink.

apps/desktop/src/hermes.test.ts

@@ -1,6 +1,6 @@
 import { afterEach, beforeEach, describe, expect, it, vi } from 'vitest'
 
-import { getSessionMessages, listAllProfileSessions, listSessions } from './hermes'
+import { listAllProfileSessions, listSessions } from './hermes'
 
 const emptySessionsResponse = {
   limit: 0,
@@ -46,15 +46,4 @@ describe('Hermes REST session helpers', () => {
       })
     )
   })
-
-  it('tags cross-profile message reads for Electron routing and backend lookup', async () => {
-    api.mockResolvedValue({ messages: [], session_id: 'session-1' })
-
-    await getSessionMessages('session-1', 'xiaoxuxu')
-
-    expect(api).toHaveBeenCalledWith({
-      path: '/api/sessions/session-1/messages?profile=xiaoxuxu',
-      profile: 'xiaoxuxu'
-    })
-  })
 })