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/run_agent/test_codex_app_server_integration.py

@@ -84,56 +84,6 @@ class TestRunConversationCodexPath:
         assert result["codex_thread_id"] == "thread-stub-1"
         assert result["codex_turn_id"] == "turn-stub-1"
 
-    def test_codex_app_server_token_usage_updates_session_accounting(self, monkeypatch):
-        def fake_run_turn(self, user_input: str, **kwargs):
-            return TurnResult(
-                final_text="done",
-                projected_messages=[{"role": "assistant", "content": "done"}],
-                turn_id="turn-usage-1",
-                thread_id="thread-usage-1",
-                token_usage_last={
-                    "totalTokens": 130,
-                    "inputTokens": 80,
-                    "cachedInputTokens": 20,
-                    "outputTokens": 25,
-                    "reasoningOutputTokens": 5,
-                },
-                model_context_window=200000,
-            )
-
-        monkeypatch.setattr(CodexAppServerSession, "run_turn", fake_run_turn)
-        monkeypatch.setattr(
-            CodexAppServerSession, "ensure_started", lambda self: "thread-usage-1"
-        )
-        agent = _make_codex_agent()
-        with patch.object(agent, "_spawn_background_review", return_value=None):
-            result = agent.run_conversation("hello")
-
-        assert result["api_calls"] == 1
-        assert result["prompt_tokens"] == 100
-        assert result["completion_tokens"] == 25
-        assert result["total_tokens"] == 130
-        assert result["input_tokens"] == 80
-        assert result["output_tokens"] == 25
-        assert result["cache_read_tokens"] == 20
-        assert result["cache_write_tokens"] == 0
-        assert result["reasoning_tokens"] == 5
-        assert result["last_prompt_tokens"] == 100
-
-        assert agent.session_api_calls == 1
-        assert agent.session_prompt_tokens == 100
-        assert agent.session_completion_tokens == 25
-        assert agent.session_total_tokens == 130
-        assert agent.session_input_tokens == 80
-        assert agent.session_output_tokens == 25
-        assert agent.session_cache_read_tokens == 20
-        assert agent.session_cache_write_tokens == 0
-        assert agent.session_reasoning_tokens == 5
-        assert agent.context_compressor.last_prompt_tokens == 100
-        assert agent.context_compressor.last_completion_tokens == 25
-        assert agent.context_compressor.last_total_tokens == 130
-        assert agent.context_compressor.context_length == 200000
-
     def test_projected_messages_are_spliced(self, fake_session):
         agent = _make_codex_agent()
         with patch.object(agent, "_spawn_background_review", return_value=None):