Add platform/src/appkit.rs with: - NSRect/NSPoint/NSSize geometry types matching AppKit's C layout - NSWindow style mask and backing store constants - NSApplicationActivationPolicy constants - AutoreleasePool RAII wrapper (creates on new, drains on drop) - App wrapper: sharedApplication, setActivationPolicy:, activateIgnoringOtherApps:, run - Window wrapper: initWithContentRect:styleMask:backing:defer:, setTitle: (via toll-free bridged CfString), makeKeyAndOrderFront:, contentView - WeAppDelegate custom ObjC class implementing applicationShouldTerminateAfterLastWindowClosed: -> YES - create_standard_window() convenience (800x600, titled/closable/ miniaturizable/resizable) - 6 unit tests covering geometry, constants, and autorelease pool Update browser main.rs to open a native macOS window titled "we". Closing the window terminates the application. Also fix pre-existing clippy macro_metavars_in_unsafe lint in msg_send! macro by binding metavariables to locals outside unsafe blocks. Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>