- Upgrade rust_cast 0.18.1 → 0.21 (switches from openssl to rustls, removing the openssl-sys dependency that blocked x86_64 cross-compile) - Split mupdf sys-lib features to Linux-only (on macOS there are no GTK symbol conflicts, and system libs don't support x86_64 cross-compile from Apple Silicon) - Update release-macos workflow to build both aarch64 and x86_64 DMGs using a matrix strategy