tests: pin ink engine in _make_tui_argv npm-bootstrap tests (post-merge semantic fix)

Main's rewritten test_tui_npm_install.py tests call _make_tui_argv expecting
the Ink/npm flow unconditionally; with the dual-engine dispatch merged in,
_resolve_tui_engine() auto-selects opentui whenever ui-opentui/dist is built
in the repo, routing the call away from the path under test (first subprocess
became 'node --version' instead of 'npm run build'). Pin the engine to ink
via an autouse fixture, mirroring the existing pinning precedent in
test_tui_resume_flow.py.

tests/hermes_cli/test_cli_active_session_limit.py

@@ -0,0 +1,41 @@
+from cli import HermesCLI
+from hermes_cli.active_sessions import (
+    active_session_registry_snapshot,
+    try_acquire_active_session,
+)
+
+
+def test_cli_claim_active_session_respects_global_limit(tmp_path, monkeypatch):
+    monkeypatch.setenv("HERMES_HOME", str(tmp_path / ".hermes"))
+    cfg = {"max_concurrent_sessions": 1}
+    held, message = try_acquire_active_session(
+        session_id="held-session",
+        surface="tui",
+        config=cfg,
+    )
+    assert message is None
+    assert held is not None
+
+    cli = object.__new__(HermesCLI)
+    cli.session_id = "new-cli-session"
+    cli.config = cfg
+    cli._active_session_lease = None
+    printed: list[str] = []
+    cli._console_print = lambda text: printed.append(text)
+
+    try:
+        assert cli._claim_active_session("cli") is False
+        assert printed == [
+            "[bold red]Hermes is at the active session limit (1/1). "
+            "Try again when another session finishes.[/]"
+        ]
+
+        held.release()
+
+        assert cli._claim_active_session("cli") is True
+        assert [entry["session_id"] for entry in active_session_registry_snapshot()] == [
+            "new-cli-session"
+        ]
+    finally:
+        held.release()
+        cli._release_active_session()