test: add unit tests for widgetWindows widget

[kh-ub-ayb]

Summary

This pr adds a new unit test suite for the widgetWindows module, covering the WidgetWindow class and global widgetWindows utility functions with 79 comprehensive tests.

Changes

• Added 79 new unit tests in js/widgets/__tests__/widgetWindows.test.js
• No changes to source code

Test Coverage

Describe Block	Tests	Coverage
Constructor (via windowFor)	11	_visible, _maximized, _rolled, _dragging, _buttons initialization; DOM elements _frame, _body, _toolbar, _widget, _drag; position cache restore
_create helper	5	Creates element with tag, className, parent append, no-parent handling
_toggleClass helper	3	Add class, remove class, toggle back/forth
addButton	8	Returns wfbtItem div, img src/dimensions/title/alt, _buttons array tracking, toolbar vs custom parent append
addDivider	2	Returns wfbtHR div, appends to toolbar
addInputButton	4	Returns input element, initial value, toolbar vs custom parent
close	4	Calls onclose, removes mouseup/mousemove/mousedown listeners
destroy	4	Removes _frame and _overlayframe from DOM, clears openWindows entry, removes event listeners
sendToCenter	2	Returns this for chaining, fallback position for zero-dimension canvas
_maximize / _restore	10	Maximize: sets _maximized, viewport dimensions, top-left positioning, saves position, contract icon. Restore: resets _maximized, expand icon, restores saved position, auto dimensions, clears _savedPos
updateTitle	1	Updates title element innerHTML
takeFocus	3	Sets zIndex 10000, opacity 1, sibling zIndex reset
isMaximized	3	False initially, true after maximize, false after restore
Other public methods	13	setPosition (styles, min-top-64, caching, chaining), isVisible, show, clear, clearScreen, getWidgetBody, getWidgetFrame, _rollup, unroll
Global functions	6	windowFor create/reuse/key fallbacks, isOpen true/empty-string

Scope

• Only js/widgets/__tests__/widgetWindows.test.js was added
• No changes to source code

Verification

• All 79 tests pass

[github-actions]

✅ All Jest tests passed! This PR is ready to merge.

[kh-ub-ayb]

@walterbender @omsuneri please review