Fix iOS target architecture detection for Intel Macs

[luapmartin]

Fix iOS Target Architecture Detection for Intel Macs

Problem

When building a Dioxus app for iOS simulator on an Intel-based Mac, the Dioxus CLI (dx) ignores the specified target architecture (x86_64-apple-ios) and always builds for aarch64-apple-ios-sim. This results in an app that cannot run on Intel-based iOS simulators, showing the error "This app needs to be updated by the developer to work on this version of iOS." (see #3962)

Solution

This PR adds host architecture detection to the Dioxus CLI and updates the iOS target selection logic to:

1. First check if a target was explicitly specified via the --target flag
2. If no target was specified, detect the host architecture and use the appropriate target:
   • x86_64-apple-ios for Intel Macs
   • aarch64-apple-ios-sim for Apple Silicon Macs

Changes

• Added a detect_host_arch() function to detect if the host is running on Apple Silicon or Intel
• Updated the iOS target selection logic in build/request.rs
• Fixed the iOS bundle target selection in cli/bundle.rs
• Enhanced the iOS tooling verification in build/verify.rs
• Added a has_target method to check if a specific target is installed

Testing

Tested on an Intel-based Mac by:

1. Building a test iOS project with the modified CLI
2. Verifying that it correctly detects the Intel Mac architecture and uses the x86_64-apple-ios target
3. Verifying that it correctly respects explicitly specified targets