Add iOS support with build scripts, toolchain, and assets

[JoshBashed]

Add iOS support for Vanilla

closes #158

This PR adds iOS support for Vanilla.

Code Modifications

1. gui/main.c

   • Use SDL's built-in main instead of a custom entry point. SDL provides iOS-specific startup behavior that we rely on.

2. gui/platform.c

   • On iOS, use os_log because stdout and stderr are not exposed in a meaningful way.
   • Wrap logging with vsnprintf to avoid using os_log directly. os_log requires privacy annotations and does not fully support standard printf format specifiers.

Build Changes

1. ios/toolchain.cmake

   • Add an iOS toolchain.

2. gui/CMakeLists.txt

   • Configure FFmpeg to build correctly on iOS and on iOS simulators.
   • Use the bundled iOS version of libxml2.
   • Create an iOS bundle with an Info.plist that supports both iOS and iPadOS.
   • Add a launch screen storyboard as required for App Store review.
   • Compile an Assets.car with the Liquid Glass app icon and merge the partial Info.plist into the final Info.plist.
   • Link the necessary Apple frameworks.
   • Copy assets into the correct layout for iOS.

3. CMakeLists.txt

   • Detect iOS and use vendored as the default on that platform.

4. .gitignore

   • Add macOS-specific ignores.

5. .github/workflows/build.yml

   • Add a macos-latest job to build iOS, since iOS builds require macOS and cannot run in Docker.
   • Use the ios/build.sh script.

Added Files

1. ios/README.md

   • Overview of building for iOS.

2. ios/LaunchScreen.storyboard

   • Simple launch screen shown while the app loads.

3. ios/Info.plist

   • Required metadata for iOS, including version, capabilities, and permissions.

4. ios/build.sh

   • Script for faster iOS builds using Ninja. It is also used in CI without being tied specifically to GitHub Actions.

5. ios/AppIcon.icon

   • Liquid Glass app icon.

[JoshBashed]

Hey, can the workflow be approved for this?

[JoshBashed]

The commit has been rebased.

[JoshBashed]

Works!

[JoshBashed]

output.mp4