Studio Mode overhaul, mic downmixing, capture reliability - Cap

Studio Mode overhaul - Movement, motion blur, and styling improvements, including new and improved cursors, motion blur for zooms and fast movement, smoother auto-zoom, squircle corners, and more.
Microphone channel downmixing - Microphone audio frames are now downmixed for better consistency across devices.
Auto-recover capture failures - Automatically recovers desktop microphone feed and ScreenCaptureKit stream failures on macOS.
macOS capture reliability - Simplified system stop error checks in screen capture to reduce spurious failures.