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/hermes_cli/test_tools_config.py

@@ -975,19 +975,6 @@ def test_toolset_has_keys_treats_no_key_providers_as_configured():
     assert _toolset_has_keys("computer_use", config) is True
 
 
-def test_web_no_prompt_when_usable_keyless():
-    """Fresh install: web works via the free Parallel MCP, so enabling the web
-    toolset should not force provider setup."""
-    with patch("tools.web_tools.check_web_api_key", return_value=True):
-        assert _toolset_needs_configuration_prompt("web", {}) is False
-
-
-def test_web_no_prompt_when_extract_backend_is_extract_capable():
-    with patch("tools.web_tools.check_web_api_key", return_value=True):
-        cfg = {"web": {"extract_backend": "parallel"}}
-        assert _toolset_needs_configuration_prompt("web", cfg) is False
-
-
 def test_computer_use_needs_configuration_when_cua_driver_post_setup_pending():
     """No-key providers can still need setup when their post_setup is unsatisfied.