Enable risc0-zkvm/client feature by default

[koxu1996]

Fixes #157.

[Avi-D-coder]

I don't want to enable prove by default because it makes rust-analyzer spin up an endless c++ complication and breaks the lsp. I am not sure why the you are hitting #157. I can build without prove.

Are you in the devshell nix develop .#risczero?

[koxu1996]

@Avi-D-coder I removed it from default features - 3bd10ad.

I tried building in the Nix shell - same result:

$ nix develop .#risczero
$ cd ./kairos-prover
$ cargo build -p kairos-prover-risc0-server
# compilation fails as described in #157

If there is no prove enabled then all Risc0 proving items are simply configured out.

[marijanp]

@koxu1996 I can't reproduce the error

[koxu1996]

@marijanp Are you compiling it without metal/cuda feature enabled?

[Avi-D-coder]

Could we rename the feature something like build cpu prover.

Proving via cpu is normally provided by r0vm installed by cargo-risc0 or nix, hence I'd like to make it clear this builds that prover again.

[koxu1996]

I'd like to make it clear this builds that prover again.

I didn't want to build prover again, but rather make ExternalProver available in the code. Therefore client feature is more suitable here:

It should be enabled by default, as it's a default fallback:

@Avi-D-coder Please check updated PR.