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>

src/specify_cli/_console.py

@@ -7,6 +7,7 @@ layer, not out of it, to avoid circular imports.
 """
 from __future__ import annotations
 
+import sys
 from collections.abc import Callable
 
 import readchar
@@ -192,7 +193,8 @@ def select_with_arrows(
 
     def run_selection_loop():
         nonlocal selected_key, selected_index
-        with Live(create_selection_panel(), console=console, transient=True, auto_refresh=False) as live:
+        _transient = sys.platform != "win32"
+        with Live(create_selection_panel(), console=console, transient=_transient, auto_refresh=False) as live:
             while True:
                 try:
                     key = get_key()