Previously, when an application became unresponsive, synchronous
cross-process UIA/MSAA calls into it would block NVDA: the UIA event
handlers raised a flood of COMErrors through comtypes (hundreds of
identical tracebacks, leaving NVDA partially dead until the app was
killed), and the main-thread focus path froze the core for several
seconds until the watchdog cancelled the call.

UIAHandler:
- Add a _catchUIAEventHandlerCOMError decorator on the five UIA event
  handlers so a COMError from an unresponsive sender is logged once at
  debug level instead of flooding out through comtypes.
- Drop UIA events whose sender's window belongs to an application the
  system reports as not responding (cheap, cached-handle check).
- Use the cached element class name on the high-frequency textChange
  path instead of a live cross-process fetch (combo box / File
  Explorer latency).

MSAA / main thread:
- Drop winEvents for a hung application at the source (beside the
  existing ghosted-window drop) so the focus ancestor walk
  (IAccessible accParent) can no longer block the core; engages as
  soon as the OS flags the app, without waiting for its DWM ghost
  window. Focus into a hung window is still announced using the
  hang-safe InternalGetWindowText caption.
- Treat IsHungAppWindow like the existing ghost check in
  isUsableWindow / Window.getPossibleAPIClasses so child windows of a
  hung app are covered too.

Add IsHungAppWindow binding, the UIA.ignoreHungWindowEvents setting
(default on) with an Advanced-panel checkbox, unit tests, user guide
entry and changelog.

Fixes nvaccess#16749

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Per review feedback from @LeonarddeR and @CyrilleB79:

- Remove the _catchUIAEventHandlerCOMError decorator and its uses.
  Deferred to a follow-up: handlers should ideally not throw, and the
  gain without it is already large (the hung-window skip prevents the
  flood in practice).
- Remove the "not responding" ui.message announcement from
  winEventToNVDAEvent. Speaking does not belong in an event-conversion
  function; a proper announcement can be a separate follow-up.
- Drop the UIA.ignoreHungWindowEvents setting (configSpec, Advanced
  panel checkbox, user guide). It mirrors the existing, unconditional
  ghost-window handling beside it; there is no legitimate reason to keep
  polling a window the system reports as not responding, so it does not
  need to be configurable.
- winEventToNVDAEvent: log the dropped hung-window event with
  log.debugWarning instead of log.debug.

The PR is now focused: drop UIA and MSAA events from a not-responding
application (beside the existing ghost-window drop) and use the cached
class name on the hot textChange path.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

- winUser.isHungAppWindow: type hints (hwnd: HWNDVal) -> bool;
  L{...} -> backticks in docstring.
- UIAHandler.utils._getCachedWindowHandleFromEvent: epytext @return: ->
  sphinx :return:; log the swallowed COMError at debug level.
- UIAHandler.utils._shouldSkipEventForHungWindow: log the swallowed
  exception at debug level.
- tests/unit/test_UIAHandler.py: NV Access full copyright header; type
  hints on _FakeElement.__init__ and cachedNativeWindowHandle.
- user_docs/en/changes.md: 'UI Automation' -> 'UIA' (per inline suggestion).

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>