Add support for risc0

[gballet]

Adds support for proving on risc0.

[Copilot]

Pull Request Overview

This PR adds support for the risc0 backend by introducing related syscall enums, host functions, build scripts, and CLI integration. Key changes include new risc0 syscall and assembly files, updated host FFI and Cargo configuration for risc0, and adjustments to the build pipeline for post-processing the risc0 executable.

Reviewed Changes

Copilot reviewed 14 out of 14 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
pkgs/state-transition-runtime/src/risc0/syscalls.zig	Added syscall, halt_reason, and keccak_mode enums for risc0.
pkgs/state-transition-runtime/src/risc0/start.s	Introduced a new startup assembly file for risc0.
pkgs/state-transition-runtime/src/risc0/risc0.ld	Provides the linker script for risc0.
pkgs/state-transition-runtime/src/risc0/lib.zig	Added host functions using inline assembly to trigger risc0 syscalls.
pkgs/state-transition-runtime/src/risc0/io.zig	Introduced IO syscall wrappers corresponding to risc0.
pkgs/state-transition-runtime/src/risc0/host/src/lib.rs	New risc0 host functions to perform prove and verify operations.
pkgs/state-transition-runtime/src/risc0/host/Cargo.toml	Updated Cargo configuration for risc0 host integration.
pkgs/state-transition-runtime/src/main.zig	Adjusted memory allocation and configuration for risc0 runtime.
pkgs/state-proving-manager/src/manager.zig	Extended the state transition opts union to support risc0.
pkgs/cli/src/main.zig	Updated CLI to select risc0 instead of powdr backend.
build/risc0.zig	Added a build script to postprocess the risc0 executable.
build.zig	Adjusted build logic to incorporate risc0 target and postbuild steps.

[Copilot]

Consider moving the declaration of 'empty_digest' before its usage in the 'halt' function to improve readability and avoid potential confusion.

Suggested change

	pub fn halt(status: u32) noreturn {
	sys_halt(&empty_digest, status);
	}
	const empty_digest = [_]u32{ 0x5c176f83, 0x53f3c062, 0x42651683, 0x340b8b7e, 0x19d2d1f6, 0xae4d7602, 0xb8c606b4, 0xb075b53d };
	const empty_digest = [_]u32{ 0x5c176f83, 0x53f3c062, 0x42651683, 0x340b8b7e, 0x19d2d1f6, 0xae4d7602, 0xb8c606b4, 0xb075b53d };
	pub fn halt(status: u32) noreturn {
	sys_halt(&empty_digest, status);
	}

[gballet]

Housekeeping tasks:

• fix the commitments so that the program does more than committing to an empty hash
• Use the mock prover so that it is possible to check the hash results, and thus let the test pass
• Fix the powdr build, or at the very least disable it until it works
• Update the documentation on how to run it
• Add something to CI
• check build mode for binary -> it's .ReleaseFast, good.

Some of these will be done in subsequent PRs.

[g11tech]

(pre) stateroot and blockroot are stil unused to verify transition it seems

[g11tech]

conceptually proof needs to be validated against pre state root and block root, since those are still being ignored in verify transition i can do a followup PR to change mock chain to add prestateroots (block roots are already there) so that it becomes handy over here

[g11tech]

lgtm, further verification changes can followup on another PR