fix(realtime)!: serialize `Realtime` to MainActor #731

Job	Run time
xcodebuild-macOS-14 (test, IOS)	9m 43s
linux (5.10)	1m 20s
Examples	4m 10s
xcodebuild (test, IOS)	5m 7s
xcodebuild (test, MAC_CATALYST)	3m 50s
xcodebuild-macOS-14 (test, MAC_CATALYST)	2m 16s
xcodebuild-macOS-14 (test, MACOS)	2m 30s
xcodebuild (test, MACOS)	3m 39s
xcodebuild-macOS-14 (test, TVOS)	2m 42s
xcodebuild (test, TVOS)	4m 23s
xcodebuild-macOS-14 (test, WATCHOS)	2m 34s
xcodebuild (test, WATCHOS)	6m 2s
xcodebuild-macOS-14 (IOS)	1m 31s
xcodebuild (IOS)	3m 58s
xcodebuild-macOS-14 (MAC_CATALYST)	2m 44s
xcodebuild (MAC_CATALYST)	5m 23s
xcodebuild-macOS-14 (MACOS)	1m 54s
xcodebuild (MACOS)	3m 48s
xcodebuild-macOS-14 (TVOS)	2m 16s
xcodebuild (TVOS)	4m 4s
xcodebuild-macOS-14 (WATCHOS)	2m 17s
xcodebuild (WATCHOS)	4m 8s
	1h 20m 19s

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