[Feature]: Add ability to specify target OS in build and build run commands for simulator

[opi-smccoole]

Feature Description

Allow specification of OS when executing build or build run. Produce the equivalent of -destination 'platform=iOS Simulator,OS=18.6,name=iPhone 16 Pro Max' for xcodebuild.

Use Cases

• Projects that have CI/CD pipelines for running tests that do not utilize the latest iOS version yet.
• Matching local test invocation to CI/CD pipeline expectations for tests that are affected by OS version (snapshot view testing for example)
• Ability to create sharable rules for AI agents that can request build or build run with a specific simulator name and version, without the user having to already have a proper instance launched and running

Example Interactions

Me: "When you generate or modify code, validate by building to the iOS Simulator using iPhone 16 Pro Max running iOS 18.6"
Agent: Uses iPhone 16 Pro Max destination and iOS 18.6 as target OS in xcodebuild commands to build.

Me: "Run test target 'X' using the iOS simulator named 'iPhone 16 Pro Max' running OS '18.6' "
Agent: Uses iPhone 16 Pro Max destination and iOS 18.6 as target OS in xcodebuild commands to build and run test target.

[github-actions]

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