Introduces a TESTNET variable to the Makefile and passes it from GitHub Actions workflows based on the chain-network input. Updates CMake build commands to include the TESTNET flag, improves help output formatting, and comments out unused genesis targets for clarity.
Renamed and reorganized CMake build profiles for consistency, removing unused Android, iOS, and MinGW profiles. Updated GitHub Actions workflows and Makefile to use new profile names and increased build parallelism for faster builds.