fix: prevent PySide6 6.11.0 segfault and CDockManager 4.5.x teardown crashes

[Copilot]

Description

Three targeted fixes for teardown crashes introduced by PySide6 6.11.0 and PySide6-QtAds 4.5.x. PySide6 6.11.0 segfaults when setParent() targets a widget mid-destruction; QtAds 4.5.x is stricter about dock widget teardown order.

Root cause (segfault): _destroyed was set after cleanup() returned, so during teardown the flag was False. This allowed _parking_parent to return console.window() (the enclosing DeveloperWidget) as a reparenting target — already being destroyed — causing setParent() to segfault.

DeveloperWidget.closeEvent → cleanup → delete_all → _delete_dock →
BecConsole.close → cleanup → registry.unregister → _park_terminal →
_parking_parent(avoid_console=True) → console.window() = DeveloperWidget
→ setParent(mid-destruction widget) → SEGFAULT

Fixes:

• bec_widget.py — move self._destroyed = True to before self.cleanup() in closeEvent(), making the flag available throughout the entire teardown chain

• bec_console.py — in _parking_parent(), skip console.window() as a parking target when window._destroyed is True, falling back to _fallback_holder instead

• basic_dock_area.py — add DockAreaWidget.cleanup() that calls delete_all() before super().cleanup(), ensuring CDockWidgets are released through the Qt ADS API (closeDockWidget / deleteDockWidget) before BECWidget.cleanup() processes them as generic children; delete_all() is idempotent so subclasses that already call it in their own cleanup() are unaffected

Related Issues

Type of Change

• Bug fix: prevent segfault in BecConsole._park_terminal with PySide6 6.11.0
• Bug fix: prevent DeviceManagerDisplayWidget / DockAreaWidget teardown crash with PySide6-QtAds 4.5.x

How to test

• Run unit tests
• Close a DeveloperWidget (containing a BecConsole) — should not segfault
• Close a DeviceManagerDisplayWidget — should not crash

Potential side effects

_destroyed = True is now set earlier in closeEvent. Any code that checked _destroyed to gate re-entrant calls during cleanup() will now correctly see True; this is the intended behavior. No other known side effects.

Screenshots / GIFs (if applicable)

N/A

Additional Comments

CI is pending maintainer approval to run on this bot-submitted PR. The prior CI run (pre-fix, SHA f4d51b62) showed exit code 139 (segfault) in test_developer_view; these fixes address that crash chain directly.

Definition of Done

• Documentation is up-to-date.

[github-actions]

Benchmark comparison

Threshold: 20% (lower is better).
Result: 0 regression(s), 1 improvement(s) beyond threshold.

No benchmark regression exceeded the configured threshold.

1 benchmark(s) improved beyond the configured threshold.

Benchmark	Baseline	Current	Change
BEC IPython client without companion app	2.21378 s	1.71133 s	-22.70%

All benchmark results

Benchmark	Baseline	Current	Change	Status
BEC IPython client with companion app	5.91908 s	5.63855 s	-4.74%	ok
BEC IPython client without companion app	2.21378 s	1.71133 s	-22.70%	🟢 improved
Import bec_widgets	0.0143291 s	0.011679 s	-18.50%	ok
tests/unit_tests/benchmarks/test_dock_area_benchmark.py::test_add_waveform_to_dock_area	0.151597 s	0.139595 s	-7.92%	ok