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.

tests/cron/test_scheduler.py

@@ -1487,7 +1487,7 @@ class TestRunJobConfigLogging:
         }
 
         # Mock heavy post-yaml work so the test only exercises the warning
-        # path. Without these mocks, run_job continues into provider
+        # path. Without these mocks, _run_job_impl continues into provider
         # resolution and MCP discovery, both of which can spawn subprocesses
         # / hit the network and have caused this test to time out on CI
         # (>30s wall clock) under load. See PR #33661 follow-up.