Lean4 runtime for RISC0

Building:

just build

Installing:

just install

Make sure you have the following environment variables set.

• LEAN_RISC0_PATH: installation path for the Lean RISC0 runtime, typically $HOME/.lean-risc0.
• RISC0_TOOLCHAIN_PATH: path to RISC0 toolchain, typically $HOME/.risc0/toolchains/v2024.1.5-cpp-x86_64-unknown-linux-gnu/riscv32im-linux-x86_64.