Add AGENTS.md for AI coding agents #2333

Job	Run time
build-examples	20m 3s
Test BridgeJS against Swift versions (swift:6.1.2, 601.0.0)	2m 56s
check-bridgejs-generated	2m 47s
Build for native target (macos-15, Xcode_16.4)	2m 29s
Test BridgeJS against Swift versions (swift:6.2, 602.0.0)	3m 42s
Build and Test (ubuntu-24.04, https://download.swift.org/development/ubuntu2404/swift-DEVELOPMENT...	13m 2s
format	31s
Build and Test (ubuntu-24.04, https://download.swift.org/swift-6.3-branch/ubuntu2404/swift-6.3-DE...	13m 6s
Build and Test (ubuntu-22.04, https://download.swift.org/swift-6.1-release/ubuntu2204/swift-6.1-R...	13m 33s
Build and Test (ubuntu-22.04, https://download.swift.org/development/ubuntu2204/swift-DEVELOPMENT...	17m 28s
deploy-examples	0s
	1h 29m 37s

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