fix: iOS app crash at startup

[the9an]

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Pull Request Details

Before this change:

• Facebook SDK .xcframeworks were not explicitly added to the Unity iOS build output.

• This sometimes caused missing framework references in Xcode, leading to build errors or runtime crashes when the app attempted to use Facebook SDK functionality.

After this change:

• Added a PostProcessBuild step to automatically include the required Facebook .xcframeworks (FBAEMKit, FBSDKCoreKit, FBSDKCoreKit_Basics, FBSDKGamingServicesKit, FBSDKLoginKit, FBSDKShareKit) in the Xcode project.

• Ensures these frameworks are both added to the build and embedded in the app bundle for runtime access.

• The script targets the UnityMainTarget to insert framework references directly into the generated Xcode project.

Test Plan

1. Build the Unity project for iOS.

2. Open the generated Xcode project.

3. Verify the Facebook .xcframeworks appear in Frameworks, Libraries, and Embedded Content under the Unity iOS target.

4. Confirm that “Embed & Sign” is set for each framework.

5. Run the app on a physical iOS device and verify that Facebook SDK features load without causing runtime crashes.