feat: add no-std feature to mina-curves crate

- Add `no-std` feature to Cargo.toml (not default)
- Add conditional `#![no_std]` attribute to lib.rs
- Enable mina-curves in no-std CI workflow

Closes: o1-labs/mina-rust#1987

Author: dannywillems

.github/workflows/no-std.yml

@@ -24,11 +24,11 @@ jobs:
           - { name: "mina-hasher", path: "hasher" } # https://github.com/o1-labs/mina-rust/issues/1994
           - { name: "mina-poseidon", path: "poseidon" } # https://github.com/o1-labs/mina-rust/issues/1996
           - { name: "mina-signer", path: "signer" } # https://github.com/o1-labs/mina-rust/issues/1995
+          - { name: "mina-curves", path: "curves" } # https://github.com/o1-labs/mina-rust/issues/1987
           # TODO: Add no-std feature to these crates
           # - { name: "wasm-types", path: "crates/wasm-types" }
           # - { name: "groupmap", path: "groupmap" } # https://github.com/o1-labs/mina-rust/issues/1985
           # - { name: "turshi", path: "turshi" } # https://github.com/o1-labs/mina-rust/issues/1986
-          # - { name: "mina-curves", path: "curves" } # https://github.com/o1-labs/mina-rust/issues/1987
           # - { name: "o1-utils", path: "utils" } # https://github.com/o1-labs/mina-rust/issues/1988
           # - { name: "internal-tracing", path: "internal-tracing" } # https://github.com/o1-labs/mina-rust/issues/1989
           # - { name: "poly-commitment", path: "poly-commitment" } # https://github.com/o1-labs/mina-rust/issues/1990

curves/Cargo.toml

@@ -14,6 +14,7 @@ default = ["asm"]
 # The MontConfig derive macro from ark_ff generates code with cfg(feature = "asm").
 # This feature enables assembly optimizations in ark_ff.
 asm = []
+no-std = []
 
 [dependencies]
 ark-bn254.workspace = true

curves/src/lib.rs

@@ -1,2 +1,4 @@
+#![cfg_attr(feature = "no-std", no_std)]
+
 pub mod named;
 pub mod pasta;