fix(mac): shrink onboarding height

apps/macos/Sources/Clawdis/Onboarding.swift

@@ -24,7 +24,7 @@ final class OnboardingController {
         let hosting = NSHostingController(rootView: OnboardingView())
         let window = NSWindow(contentViewController: hosting)
         window.title = UIStrings.welcomeTitle
-        window.setContentSize(NSSize(width: 630, height: 805))
+        window.setContentSize(NSSize(width: 630, height: 684))
         window.styleMask = [.titled, .closable, .fullSizeContentView]
         window.titlebarAppearsTransparent = true
         window.titleVisibility = .hidden