Crash on macOS Tahoe 26.6: MiddleAlignedCell receives _visualProviderIfExists

[ShunRao010]

## Environment

• macOS: Tahoe 26.6
• Hardware: Apple Silicon (M4 Pro)
• WinDiskWriter: current source from main
• Xcode: Xcode 26.x

## Problem

WinDiskWriter crashes immediately on launch on macOS Tahoe 26.6.

Launching the executable directly from Terminal produces:

*** Terminating app due to uncaught exception 'NSInvalidArgumentException',
reason: '-[MiddleAlignedCell _visualProviderIfExists]:
unrecognized selector sent to instance ...'

libc++abi: terminating due to uncaught exception of type NSException

I also see this runtime warning:
_objc: Class DiskManager is implemented in both
/System/Library/PrivateFrameworks/ProDisplayLibrary.framework/...
and
WinDiskWriter.app/..._
The DiskManager warning may be unrelated to the actual crash.

**Investigation**

MiddleAlignedCell is currently declared as:
_@interface MiddleAlignedCell : NSCell_
It is then used as the cell of an NSTextField.

On macOS Tahoe, AppKit appears to send the private selector:
__visualProviderIfExists_
to the cell object, which causes the crash because the custom NSCell subclass does not respond to it.

**Minimal workaround / potential fix**
I changed:
_@interface MiddleAlignedCell : NSCell_
to:
_@interface MiddleAlignedCell : NSTextFieldCell_
No other source changes were required.

**Verification**
After this one-line change:

* the project builds successfully with Xcode 26.x;
* WinDiskWriter launches successfully on macOS Tahoe 26.6;
* I successfully used the rebuilt application to create a Windows 11 installation USB;
* the USB successfully booted into Windows Setup.

This therefore appears to be an AppKit compatibility issue involving the custom NSCell subclass on macOS Tahoe.

I have only tested the change on an M4 Pro running macOS Tahoe 26.6, so regression testing on older macOS versions would still be useful.