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/tools/test_dockerfile_pid1_reaping.py

@@ -172,31 +172,6 @@ def test_dockerfile_preinstalls_gateway_messaging_dependencies(dockerfile_text):
     )
 
 
-def test_dockerfile_preinstalls_matrix_dependencies(dockerfile_text):
-    sync_steps = [
-        step for step in _run_steps(dockerfile_text)
-        if "uv sync" in step and "--no-install-project" in step
-    ]
-
-    assert sync_steps, "Dockerfile must install Python dependencies with uv sync"
-    assert any("--extra matrix" in step for step in sync_steps), (
-        "Published Docker images must preload the [matrix] extra so the "
-        "Matrix gateway has mautrix[encryption]/python-olm available at "
-        "runtime instead of relying on first-boot lazy installation into "
-        "the container venv (#30399)."
-    )
-
-
-def test_dockerfile_installs_matrix_native_build_dependencies(dockerfile_text):
-    instructions = _instruction_text(dockerfile_text)
-
-    for package in ("libolm-dev", "cmake", "g++", "make"):
-        assert package in instructions, (
-            "Docker image must include native build dependencies needed by "
-            f"python-olm when preinstalling the [matrix] extra (#30399): {package}"
-        )
-
-
 def test_dockerfile_preinstalls_hindsight_memory_dependency(dockerfile_text):
     sync_steps = [
         step for step in _run_steps(dockerfile_text)