feat: add nix flake

[getchoo]

this adds a standard nix flake for building both the binary and docker image - all with cross compiling from any system to x86_64 and aarch64

another nice change is redis can now be run from a devShell by entering it and running daemons (see the comment in ./nix/dev.nix)

[ryanccn]

Cross-compilation from darwin does not work; outputs darwin executable

[ryanccn]

Building valfisk-docker on macOS still results in a macOS Mach-O binary in a Linux Docker image. Is there any way around this?

Also, how are you supposed to use the cross packages? Doing nix build .#legacyPackages.x86_64-linux.cross.valfisk didn't really work for me.

[getchoo]

Building valfisk-docker on macOS still results in a macOS Mach-O binary in a Linux Docker image. Is there any way around this?

for some reason i thought this would make a macos docker image...lol
anyways, i've made a new set of packages in legacyPackages (since they really shouldn't be used outside of this flake) that will build a static version of valfisk for linux from any system, along with an accompanying docker image. you can build these with nix build .#valfisk-static and nix build .#valfisk-docker

Also, how are you supposed to use the cross packages? Doing nix build .#legacyPackages.x86_64-linux.cross.valfisk didn't really work for me.

see above; i've slightly changed the approach here since we only really need these for docker images and compiling to a static linux binary

[ryanccn]

rip