fix: disable Rich Live transient mode on Windows to prevent PS 5.1 hang (#2938)

* fix: disable Rich Live transient mode on Windows to prevent PS 5.1 hang

PowerShell 5.1's legacy console host does not reliably support VT escape
sequences. Rich's Live(transient=True) attempts cursor restoration on
context exit, which hangs indefinitely on that console.

Set transient=False when sys.platform == 'win32' in both init.py (progress
tracker) and _console.py (select_with_arrows). The only cosmetic effect is
that progress output remains visible after completion on Windows.

Fixes #2927

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

* test: address review feedback on test quality

- Use captured['transient'] instead of .get() for clearer KeyError on failure
- Source guards now assert both the platform check AND transient=_transient usage
- Remove unused imports (MagicMock retained as it's used, removed pytest)

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

* test: use regex in source guards for resilience to formatting changes

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

* test: use single DOTALL regex to verify assignment flows into Live()

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

* fix: skip duplicate tracker print on Windows when transient=False

When transient is False, Rich leaves the Live output on screen. The
subsequent console.print(tracker.render()) would duplicate it. Gate
it behind _transient so Windows users see the tracker exactly once.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

---------

Co-authored-by: Manfred Riem <mnriem@users.noreply.github.com>
Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

tests/test_live_transient_windows.py

@@ -0,0 +1,90 @@
+"""Tests for Rich Live transient=False on Windows (GitHub issue #2927).
+
+PowerShell 5.1's legacy console host does not support VT escape sequences
+reliably.  Rich's ``Live(transient=True)`` attempts cursor restoration on
+exit, which hangs indefinitely on that console.  The fix disables transient
+mode when ``sys.platform == "win32"``.
+
+These tests patch ``sys.platform`` and intercept the ``Live`` constructor
+to verify the correct ``transient`` value reaches Rich.
+"""
+
+from __future__ import annotations
+
+from pathlib import Path
+from unittest.mock import MagicMock, patch
+
+
+# ---------------------------------------------------------------------------
+# _console.py — Live in the select_with_arrows helper
+# ---------------------------------------------------------------------------
+
+
+def _invoke_select_with_arrows(platform: str) -> bool:
+    """Patch sys.platform and Live, invoke select_with_arrows, return transient kwarg."""
+    captured = {}
+
+    mock_live_instance = MagicMock()
+    mock_live_instance.__enter__ = MagicMock(return_value=mock_live_instance)
+    mock_live_instance.__exit__ = MagicMock(return_value=False)
+
+    def fake_live(*args, **kwargs):
+        captured.update(kwargs)
+        return mock_live_instance
+
+    # Patch readchar so the loop immediately returns "enter"
+    import readchar
+
+    with (
+        patch("sys.platform", platform),
+        patch("specify_cli._console.Live", side_effect=fake_live),
+        patch("specify_cli._console.readchar.readkey", return_value=readchar.key.ENTER),
+    ):
+        from specify_cli._console import select_with_arrows
+
+        select_with_arrows({"a": "Option A", "b": "Option B"}, "Pick one", "a")
+
+    return captured["transient"]
+
+
+class TestSelectWithArrowsLiveTransient:
+    """Verify that select_with_arrows passes transient=False on Windows."""
+
+    def test_transient_false_on_windows(self):
+        assert _invoke_select_with_arrows("win32") is False
+
+    def test_transient_true_on_linux(self):
+        assert _invoke_select_with_arrows("linux") is True
+
+    def test_transient_true_on_macos(self):
+        assert _invoke_select_with_arrows("darwin") is True
+
+
+# ---------------------------------------------------------------------------
+# init.py — verify source contains the platform guard (regression check)
+# ---------------------------------------------------------------------------
+
+
+class TestSourceContainsPlatformGuard:
+    """Ensure the platform guard feeds into the Live() transient kwarg."""
+
+    # Single DOTALL regex: _transient assigned from win32 check, then used in Live()
+    _GUARD_RE = r"_transient\s*=\s*sys\.platform\s*!=\s*['\"]win32['\"].*Live\(.*transient\s*=\s*_transient"
+
+    def test_init_has_win32_guard(self):
+        """init.py must assign _transient from platform check and pass it to Live."""
+        import re
+
+        init_src = Path(__file__).resolve().parent.parent / "src" / "specify_cli" / "commands" / "init.py"
+        content = init_src.read_text(encoding="utf-8")
+        assert re.search(self._GUARD_RE, content, re.DOTALL)
+
+    def test_console_has_win32_guard(self):
+        """_console.py must assign _transient from platform check and pass it to Live."""
+        import re
+
+        console_src = Path(__file__).resolve().parent.parent / "src" / "specify_cli" / "_console.py"
+        content = console_src.read_text(encoding="utf-8")
+        assert re.search(self._GUARD_RE, content, re.DOTALL)
+        assert re.search(r"transient\s*=\s*_transient", content)
+        assert "transient=_transient" in content