Documentation: Add macOS version requirement for building AppKit in BuildInstructionsLadybird.md

[semicube]

Just a small add to BuildInstructionsLadybird.md. MacOS Sonoma (14.0) or above is required to build the AppKit chrome.

It was not building on my machine (MacOS Ventura 13.6) and gave the following build error:

/Users/abi/Stuffs/Cloned/ladybird/Ladybird/AppKit/UI/SearchPanel.mm:66:36: error: use of undeclared identifier 'NSBezelStyleAccessoryBarAction'
   66 |         [search_done setBezelStyle:NSBezelStyleAccessoryBarAction];
      |                                    ^

Reason being that NSBezelStyleAccessoryBarAction is only available for macOS 14+.

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[ADKaster]

@trflynn89 Does using this bezel style limit our minimum deployment version as well? Should we do some if available() hackery to use a different style on older macOS versions?

[trflynn89]

This one is a bit unfortunate - I was thinking we should set CMAKE_OSX_DEPLOYMENT_TARGET to something reasonable, and then we'd get a compile error anytime we try to use an API that is newer than that version without an @available check. But this particular enum value has no such availability marker:

/// A bezel style that is suitable for accessory and scope bars. This style is typically used for buttons that perform an action or for pop-up buttons.
NSBezelStyleAccessoryBarAction = 12,

Compared to a value defined earlier in the enum:

/// The appearance of this bezel style is automatically determined based on the button's contents and position within the window. This bezel style is the default for all button initializers.
NSBezelStyleAutomatic API_AVAILABLE(macos(14.0)) = 0,

(Which, if I set CMAKE_OSX_DEPLOYMENT_TARGET to 13.0, I do get a compile error about using NSBezelStyleAutomatic without checking availability.)

That said, macOS Ventura is also likely to be end-of-life by the time we reach alpha in 2026.

[shlyakpavel]

@trflynn89 While the code details are important, this PR is focused on documentation, and, in my opinion, it looks good to merge as-is.