Update gitignore for macOS build artifacts

[draco892]

This pull request updates .gitignore to ignore the files and directories generated during macOS compilation and application packaging.

It adds rules for the generated macOS binaries, libraries, support files, .app bundles, and packaging script backup files. Existing entries were also reorganized into clearer sections.

This keeps the working tree clean after a macOS build and prevents generated artifacts from being accidentally committed.

See: #22287

[zisoft]

This occurs when building with MacPorts. The homebrew based build process creates all files under ./build.

The better solution would be to update the package building script for MacPorts to use the build directory (@MStraeten ?)

[zisoft]

I think it would be sufficient to edit ./packaging/macosx/darktable.bundle and change the destination for the package:

<?xml version="1.0"?>
<app-bundle>
  <meta>
    <prefix name="default">/opt/local</prefix>
    <prefix name="dt">/usr/local</prefix>
    <destination overwrite="yes">../../build/macosx/package</destination>
    <run-install-name-tool/>
    <gtk>gtk+-3.0</gtk>
  </meta>
  ...

(this is untested, I don't use MacPorts)

[victoryforce]

@draco892 - Instead of merging master into your feature branch, use rebase to move your local commits on top of the latest master. This keeps a clean, straight line of history without extra merge nodes.

[zisoft]

@draco892 : I don't think that the .gitignore file needs to be updated.

Did you try my suggestion above?