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.

gateway/platforms/base.py

@@ -33,7 +33,6 @@ _AUDIO_EXTS = frozenset({'.ogg', '.opus', '.mp3', '.wav', '.m4a', '.flac'})
 # delivered as a regular document.
 _TELEGRAM_AUDIO_ATTACHMENT_EXTS = frozenset({'.mp3', '.m4a'})
 _TELEGRAM_VOICE_EXTS = frozenset({'.ogg', '.opus'})
-_POST_DELIVERY_CALLBACK_TIMEOUT_SECONDS = 30.0
 
 
 def _platform_name(platform) -> str:
@@ -1545,13 +1544,6 @@ class SendResult:
     message_id: Optional[str] = None
     error: Optional[str] = None
     raw_response: Any = None
-    # Adapter-specific metadata.  Cross-layer contracts that affect delivery
-    # semantics must be documented at the producer and consumer sites.  Current
-    # known contract: Telegram edit overflow partials set
-    # raw_response["partial_overflow"] with delivered_chunks, total_chunks,
-    # last_message_id, delivered_prefix, and continuation_message_ids so the
-    # stream consumer can send the missing tail instead of marking a clipped
-    # response complete.
     retryable: bool = False  # True for transient connection errors — base will retry automatically
     # When the adapter had to split an oversized payload across multiple
     # platform messages (e.g. Telegram edit_message overflow split-and-deliver),
@@ -1803,26 +1795,11 @@ class BasePlatformAdapter(ABC):
 
     # Whether this platform renders triple-backtick fenced code blocks (i.e.
     # ``format_message`` translates/preserves markdown fences into a real code
-    # block).  Capability flag for markdown-aware presentation choices.
+    # block).  Drives presentation choices like rendering a ``terminal`` tool
+    # call's command as a ```bash block instead of a flat preview line.
     # Default False (plain-text platforms); markdown-rendering adapters set True.
-    # Tool-progress uses this to render a terminal command as a bare fenced code
-    # block (no language tag — Slack mrkdwn would print the tag as a literal
-    # first code line).  Plain-text platforms fall back to the short truncated
-    # preview (see gateway/run.py progress_callback).
     supports_code_blocks: bool = False
 
-    # The command prefix users can always TYPE on this platform to reach
-    # Hermes commands.  Default "/" (most platforms deliver "/approve" etc.
-    # as plain message text).  Platforms where typing a leading "/" is
-    # intercepted or restricted by the client (Slack blocks native slash
-    # commands inside threads; Matrix clients reserve "/" for client-local
-    # commands) ship a "!" alias rewrite in their adapter and set this to
-    # "!" so user-facing instruction text ("Reply `!approve` ...") tells
-    # users the form that actually works everywhere.  Capability flag —
-    # shared prompt builders read it via getattr(adapter,
-    # "typed_command_prefix", "/"); no per-platform branching at call sites.
-    typed_command_prefix: str = "/"
-
     def __init__(self, config: PlatformConfig, platform: Platform):
         self.config = config
         self.platform = platform
@@ -4482,15 +4459,6 @@ class BasePlatformAdapter(ABC):
             except Exception:
                 pass  # Last resort — don't let error reporting crash the handler
         finally:
-            # Stop typing before any deferred callback work.  Post-delivery
-            # callbacks may perform platform I/O; a stuck callback must not
-            # leave the typing refresh task running indefinitely.
-            await _stop_typing_task()
-            try:
-                if hasattr(self, "stop_typing"):
-                    await self.stop_typing(event.source.chat_id)
-            except Exception:
-                pass
             # Fire any one-shot post-delivery callback registered for this
             # session (e.g. deferred background-review notifications).
             #
@@ -4518,12 +4486,11 @@ class BasePlatformAdapter(ABC):
                 try:
                     _post_result = _post_cb()
                     if inspect.isawaitable(_post_result):
-                        await asyncio.wait_for(
-                            _post_result,
-                            timeout=_POST_DELIVERY_CALLBACK_TIMEOUT_SECONDS,
-                        )
-                except (asyncio.TimeoutError, Exception):
+                        await _post_result
+                except Exception:
                     pass
+            # Stop typing indicator
+            await _stop_typing_task()
             # Also cancel any platform-level persistent typing tasks (e.g. Discord)
             # that may have been recreated by _keep_typing after the last stop_typing()
             try:
@@ -4681,7 +4648,6 @@ class BasePlatformAdapter(ABC):
         guild_id: Optional[str] = None,
         parent_chat_id: Optional[str] = None,
         message_id: Optional[str] = None,
-        role_authorized: bool = False,
     ) -> SessionSource:
         """Helper to build a SessionSource for this platform."""
         # Normalize empty topic to None
@@ -4702,7 +4668,6 @@ class BasePlatformAdapter(ABC):
             guild_id=str(guild_id) if guild_id else None,
             parent_chat_id=str(parent_chat_id) if parent_chat_id else None,
             message_id=str(message_id) if message_id else None,
-            role_authorized=role_authorized,
         )
     
     @abstractmethod