fix: use `export type` for SwiftRuntimeThreadChannel re-export #2627

Job	Run time
format	34s
prettier	8s
check-bridgejs-generated	2m 40s
Test BridgeJS against Swift versions (swift:6.1.2, 601.0.0)	3m 10s
Test BridgeJS against Swift versions (swift:6.2, 602.0.0)	3m 16s
Test BridgeJS against Swift versions (swift:6.3, 603.0.0)	3m 8s
Build and Test (ubuntu-22.04, https://download.swift.org/development/ubuntu2204/swift-DEVELOPMENT...	17m 51s
build-examples	19m 25s
Build and Test (ubuntu-24.04, https://download.swift.org/development/ubuntu2404/swift-DEVELOPMENT...	13m 59s
Build and Test (ubuntu-24.04, https://download.swift.org/swift-6.3-branch/ubuntu2404/swift-6.3-DE...	12m 28s
Build and Test (ubuntu-22.04, https://download.swift.org/swift-6.1-release/ubuntu2204/swift-6.1-R...	12m 27s
Build for native target (macos-15, Xcode_16.4)	2m 12s
deploy-examples	0s
	1h 31m 18s

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