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/agent/test_display.py

@@ -12,7 +12,6 @@ from agent.display import (
     set_tool_preview_max_len,
     _render_inline_unified_diff,
     _summarize_rendered_diff_sections,
-    _used_free_parallel,
     render_edit_diff_with_delta,
 )
 
@@ -172,46 +171,6 @@ class TestCuteToolMessagePreviewLength:
         assert "[error]" not in line
 
 
-class TestWebProviderLabel:
-    """The free-path "Parallel search"/"Parallel fetch" verb labeling."""
-
-    def test_free_search_verb_is_parallel(self):
-        result = json.dumps({"success": True, "data": {"web": []}, "provider": "parallel"})
-        line = get_cute_tool_message("web_search", {"query": "hello"}, 0.1, result=result)
-        assert "Parallel search" in line
-        assert "hello" in line
-
-    def test_paid_search_verb_is_plain(self):
-        result = json.dumps({"success": True, "data": {"web": [{"url": "u"}]}})
-        line = get_cute_tool_message("web_search", {"query": "hi"}, 0.1, result=result)
-        assert "Parallel" not in line
-        assert "search" in line
-
-    def test_missing_result_verb_is_plain(self):
-        line = get_cute_tool_message("web_search", {"query": "hello"}, 0.1)
-        assert "Parallel" not in line
-        assert "search" in line
-
-    def test_helper_is_parallel_free_specific(self):
-        # Only Parallel's free MCP path marks results; nothing else does.
-        assert _used_free_parallel(json.dumps({"provider": "parallel"})) is True
-        assert _used_free_parallel(json.dumps({"provider": "exa"})) is False
-        assert _used_free_parallel(json.dumps({"provider": "firecrawl"})) is False
-        assert _used_free_parallel(json.dumps({"success": True, "data": {}})) is False
-        assert _used_free_parallel('not json') is False
-        assert _used_free_parallel(None) is False
-
-    def test_free_extract_verb_is_parallel(self):
-        result = json.dumps({"results": [{"url": "u", "content": "x"}], "provider": "parallel"})
-        line = get_cute_tool_message("web_extract", {"urls": ["https://a.test"]}, 0.1, result=result)
-        assert "Parallel fetch" in line
-
-    def test_paid_extract_verb_is_plain(self):
-        result = json.dumps({"results": [{"url": "u", "content": "x"}]})
-        line = get_cute_tool_message("web_extract", {"urls": ["https://a.test"]}, 0.1, result=result)
-        assert "Parallel" not in line
-
-
 class TestEditDiffPreview:
     def test_extract_edit_diff_for_patch(self):
         diff = extract_edit_diff("patch", '{"success": true, "diff": "--- a/x\\n+++ b/x\\n"}')