Add event handling to WeView (custom NSView subclass): - acceptsFirstResponder override (returns YES for key event delivery) - keyDown: logs key character and keyCode to stdout - mouseDown:/mouseUp:/mouseMoved: log view-local coordinates to stdout Add WeWindowDelegate (NSWindowDelegate): - windowDidResize: marks content view as needing display - windowShouldClose: returns YES (explicit close handling) Add Window helper methods: - set_delegate() for installing window delegates - set_accepts_mouse_moved_events() for mouse move tracking Update browser main.rs: - Install window delegate for resize handling - Enable mouse-moved event delivery 5 new tests for class registration, selector response, and first responder. Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>