Add macOS native lazy file pasteboard write via NSPasteboardItemDataProvider

[guiyanakuang]

Closes #3929

Summary

• Add LazyFilePasteboardProvider implementing NSPasteboardItemDataProvider in Swift for deferred/lazy file data provision on macOS pasteboard
• Add writeFilesToPasteboard(count, resolver) native function that accepts a Kotlin callback (index, buffer, bufferSize) -> length, keeping lazy resolution logic in Kotlin
• Add JNA bindings (FileResolverCallback) and test instrumentation (getProvideDataCallCount / resetProvideDataCallCount)
• Add MacosNativePasteboardTest with 7 tests covering: write validation, JVM clipboard readback, CrossPaste marker, and laziness proof (data provider not called during write, only on read)
• Fix JBR AWT shutdown race crash (SIGSEGV in setBusy) when running tests in isolation via @BeforeAll/@AfterAll lifecycle hooks

Test plan

• All 7 MacosNativePasteboardTest tests pass in isolation
• All 7 tests pass in full test suite
• No SIGSEGV crash on test process exit
• ./gradlew ktlintCheck passes
• ./gradlew build passes