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.

scripts/whatsapp-bridge/bridge.js

@@ -24,8 +24,7 @@ import { Boom } from '@hapi/boom';
 import pino from 'pino';
 import path from 'path';
 import { mkdirSync, readFileSync, writeFileSync, existsSync, readdirSync, unlinkSync } from 'fs';
-import { fileURLToPath } from 'url';
-import { randomBytes, createHash } from 'crypto';
+import { randomBytes } from 'crypto';
 import { execSync } from 'child_process';
 import { tmpdir } from 'os';
 import qrcode from 'qrcode-terminal';
@@ -46,28 +45,9 @@ const WHATSAPP_DEBUG =
 
 const PORT = parseInt(getArg('port', '3000'), 10);
 const SESSION_DIR = getArg('session', path.join(process.env.HOME || '~', '.hermes', 'whatsapp', 'session'));
-// Cache directories: the Python gateway passes the profile-aware paths via
-// env (HERMES_HOME-aware, new cache/ layout).  Fall back to the legacy
-// hardcoded locations for bridges launched outside the gateway.
-const IMAGE_CACHE_DIR = process.env.HERMES_IMAGE_CACHE_DIR
-  || path.join(process.env.HOME || '~', '.hermes', 'image_cache');
-const DOCUMENT_CACHE_DIR = process.env.HERMES_DOCUMENT_CACHE_DIR
-  || path.join(process.env.HOME || '~', '.hermes', 'document_cache');
-const AUDIO_CACHE_DIR = process.env.HERMES_AUDIO_CACHE_DIR
-  || path.join(process.env.HOME || '~', '.hermes', 'audio_cache');
-
-// Self-hash of this script file.  Reported in /health so the Python gateway
-// can detect a running bridge that predates the current bridge.js and
-// restart it instead of silently reusing stale code (stale-bridge trap:
-// `hermes update` updates bridge.js on disk but a long-lived bridge process
-// keeps serving the old behavior forever).
-let SCRIPT_HASH = '';
-try {
-  SCRIPT_HASH = createHash('sha256')
-    .update(readFileSync(fileURLToPath(import.meta.url)))
-    .digest('hex')
-    .slice(0, 16);
-} catch {}
+const IMAGE_CACHE_DIR = path.join(process.env.HOME || '~', '.hermes', 'image_cache');
+const DOCUMENT_CACHE_DIR = path.join(process.env.HOME || '~', '.hermes', 'document_cache');
+const AUDIO_CACHE_DIR = path.join(process.env.HOME || '~', '.hermes', 'audio_cache');
 const PAIR_ONLY = args.includes('--pair-only');
 const WHATSAPP_MODE = getArg('mode', process.env.WHATSAPP_MODE || 'self-chat'); // "bot" or "self-chat"
 const ALLOWED_USERS = parseAllowedUsers(process.env.WHATSAPP_ALLOWED_USERS || '');
@@ -720,7 +700,6 @@ app.get('/health', (req, res) => {
     status: connectionState,
     queueLength: messageQueue.length,
     uptime: process.uptime(),
-    scriptHash: SCRIPT_HASH,
   });
 });