Switch ARM64 build from cross-compiling on macos-latest (Intel) to
native compilation on macos-14 (M1). Updates platform checks to
use contains() so signing works on both macOS runner types.
Gracefully handle missing/invalid Apple Developer certificates instead
of failing the entire build. Detects secret availability, validates
certificate file size, makes import failures non-fatal, and splits
each variant into signed/unsigned conditional paths.
Builds macOS (ARM64 + x64) and Windows via tauri-apps/tauri-action.
Supports full/tech variants, optional code signing, and automatic
GitHub Release creation on tag push.
