Fix Wi-Fi/Bluetooth toggle shifting on L2 pages

[Luckman-Khan]

Added HorizontalAlignment=Stretch to ContentPresenter#PageHeader to ensure the header always takes full width, keeping the on/off toggle pinned to the right edge consistently.

[m417z]

@TheGamer1445891 please take a look.

[TheGamer1445891]

@TheGamer1445891 please take a look.

i plan to rework (re-do) the entire theme to fix all the bugs and make the theme look more native.

[TheGamer1445891]

@Luckman-Khan i have added this fix in my re-builded theme, so please wait for the new update (if i could finish it)

[TheGamer1445891]

turns out this doesnt do anything (the header's switch buttons will still be mis-aligned for some reason)

[Luckman-Khan]

Updated the PR with a different fix.

The previous HorizontalAlignment=Stretch rule on ContentPresenter#PageHeader did not actually constrain the header content, so I replaced it with ContentControl#PageHeaderContentControl Width=64. I tested this locally in Windhawk textual mode, and it keeps the Wi-Fi/Bluetooth L2 page toggle aligned to the right edge.

[TheGamer1445891]

Updated the PR with a different fix.

The previous HorizontalAlignment=Stretch rule on ContentPresenter#PageHeader did not actually constrain the header content, so I replaced it with ContentControl#PageHeaderContentControl Width=64. I tested this locally in Windhawk textual mode, and it keeps the Wi-Fi/Bluetooth L2 page toggle aligned to the right edge.

@Luckman-Khan i tested it and turns out it still doesnt do anything and still makes the control center header switch button misaligned.
make sure to restart ShellHost.exe when applying this to see if works or not (since i tested it by restarting shellhost and it looks like it doesnt work/still misaligned).

[Luckman-Khan]

I retested with ShellHost.exe restarted and confirmed a before/after on my setup: removing Width=64 makes the L2 toggle shift inward, adding it back moves it to the far right.

Could this be a Windows build / visual tree difference? To verify whether the selector applies on your setup, can you try temporarily adding Background:=Red to ContentControl#PageHeaderContentControl? If it does not show, then this selector is not matching your ShellHost tree and we need a more specific/different target.