Standardized build target names and artifact directory paths across Linux, macOS (Intel and ARM), and Windows GitHub Actions workflows. Updated Dockerfile to use 'gcc-linux-armv8' as the build target and added 'bison' to dependencies for improved build environment consistency.
Changed output binary names in CMakeLists.txt from zanod/simplewallet to lethean-* variants, with testnet-specific names when applicable. Updated GitHub Actions workflows to upload lethean-* artifacts instead of the previous explicit binary names.
Changed build commands and artifact directories in macOS and Windows GitHub Actions workflows to use new target names and paths. Removed 'connectivity_tool' from CLI artifacts.
