Webserver: JSON batching, removed MD5 blocking, simplified flow control Memory: QR code caching, WiFi scan optimization, cover buffer leak fix EPUB: Fixed errant underlining before styled inline elements Flash screen: Version string overflow fix, half refresh for cleaner display Upstream merges: - PR #522: HAL abstraction layer (HalDisplay, HalGPIO) - PR #603: Sunlight fading fix toggle in Display settings