fix(Drawer): account for cursor position in resize

[kmcfaul]

What: Closes #12438

This bug appears to be unrelated to the unified changes, it was just easier to see on the pill resizable drawers. The issue stems from the logic making the drag edge align with the panel edge and not the initial cursor position on the splitter. So the initial jump was the drawer's edge re-aligning on the cursor position.

Debugging assisted by Cursor AI

Summary by CodeRabbit

• Refactor
  • Improved the internal state management for drawer panel resize operations to enhance stability during user interactions.

[coderabbitai]

Walkthrough

DrawerPanelContent resize logic is refactored to use a single persistent resizeState ref (holding initialPointerPos, initialPanelSize, and currWidth) replacing local variables. A new setInitialResizeState helper captures initial panel dimensions on drag start; handleControlMove and all end/keyboard handlers read from and write to this ref.

DrawerPanelContent resize state refactor

Layer / File(s)	Summary
resizeState ref declaration and initialization helpers packages/react-core/src/components/Drawer/DrawerPanelContent.tsx	Declares the resizeState ref with initialPointerPos, initialPanelSize, and currWidth fields; introduces the setInitialResizeState helper that reads getBoundingClientRect() (selecting height for bottom position, width otherwise); updates both the touch-start and mouse-down handlers to call it in place of the previous ad-hoc local-variable initialization.
handleControlMove and resize completion handlers packages/react-core/src/components/Drawer/DrawerPanelContent.tsx	Refactors handleControlMove to compute delta and newSize from resizeState.current, applies the flex-basis CSS token and disables overflow anchoring for bottom resizing, then writes the result back to resizeState.current.currWidth; updates the mouseup, touchend, and keyboard handlers to pass resizeState.current.currWidth to the onResize callback instead of the now-removed local currWidth variable.

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~10 minutes

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title clearly and concisely describes the main fix: addressing cursor position handling in the Drawer resize functionality.
Linked Issues check	✅ Passed	The PR correctly addresses issue #12438 by refactoring resize logic to properly track initial cursor position via resizeState ref, eliminating the drawer jump on resize initiation.
Out of Scope Changes check	✅ Passed	All changes are directly related to fixing the drawer resize cursor position bug; no unrelated modifications detected in DrawerPanelContent.tsx.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.

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✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests

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[patternfly-build]

Preview: https://pf-react-pr-12506.surge.sh

A11y report: https://pf-react-pr-12506-a11y.surge.sh