Add AGENTS.md for AI coding agents #2332

Job	Run time
prettier	7s
build-examples	17m 41s
format	34s
Test BridgeJS against Swift versions (swift:6.1.2, 601.0.0)	2m 58s
check-bridgejs-generated	2m 34s
Build for native target (macos-15, Xcode_16.4)	2m 17s
Test BridgeJS against Swift versions (swift:6.2, 602.0.0)	3m 11s
Build and Test (ubuntu-22.04, https://download.swift.org/development/ubuntu2204/swift-DEVELOPMENT...	17m 16s
Build and Test (ubuntu-22.04, https://download.swift.org/swift-6.1-release/ubuntu2204/swift-6.1-R...	14m 3s
Build and Test (ubuntu-24.04, https://download.swift.org/swift-6.3-branch/ubuntu2404/swift-6.3-DE...	13m 1s
Build and Test (ubuntu-24.04, https://download.swift.org/development/ubuntu2404/swift-DEVELOPMENT...	13m 17s
deploy-examples	1s
	1h 27m 0s

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