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.

agent/transports/codex_app_server_session.py

@@ -72,9 +72,6 @@ class TurnResult:
     error: Optional[str] = None  # Set if turn ended in a non-recoverable error
     turn_id: Optional[str] = None
     thread_id: Optional[str] = None
-    token_usage_last: Optional[dict[str, Any]] = None
-    token_usage_total: Optional[dict[str, Any]] = None
-    model_context_window: Optional[int] = None
     # Hint to the caller that the underlying codex subprocess is likely
     # wedged (turn-level timeout fired, post-tool watchdog tripped, or
     # token-refresh failure killed the child). The caller should retire
@@ -504,7 +501,6 @@ class CodexAppServerSession:
                     pending = self._client.take_notification(timeout=0)
                     if pending is None:
                         break
-                    _apply_token_usage_notification(result, pending)
                     self._track_pending_file_change(pending)
                     proj = projector.project(pending)
                     if proj.messages:
@@ -540,8 +536,6 @@ class CodexAppServerSession:
                 except Exception:  # pragma: no cover - display callback
                     logger.debug("on_event callback raised", exc_info=True)
 
-            _apply_token_usage_notification(result, note)
-
             # Track in-progress fileChange items so the approval bridge
             # can surface a real change summary when codex requests
             # approval (the approval params themselves don't carry the
@@ -808,30 +802,6 @@ class CodexAppServerSession:
         return cached
 
 
-def _apply_token_usage_notification(result: TurnResult, note: dict) -> None:
-    """Capture Codex app-server token usage updates for caller accounting.
-
-    Codex does not put token usage on turn/completed. It emits a separate
-    thread/tokenUsage/updated notification containing cumulative totals and
-    the latest turn breakdown.
-    """
-    if not isinstance(note, dict) or note.get("method") != "thread/tokenUsage/updated":
-        return
-    params = note.get("params") or {}
-    token_usage = params.get("tokenUsage") or {}
-    if not isinstance(token_usage, dict):
-        return
-    last = token_usage.get("last")
-    total = token_usage.get("total")
-    if isinstance(last, dict):
-        result.token_usage_last = dict(last)
-    if isinstance(total, dict):
-        result.token_usage_total = dict(total)
-    window = token_usage.get("modelContextWindow")
-    if isinstance(window, int) and window > 0:
-        result.model_context_window = window
-
-
 def _approval_choice_to_codex_decision(choice: str) -> str:
     """Map Hermes approval choices onto codex's CommandExecutionApprovalDecision
     / FileChangeApprovalDecision wire values.