feat: add Nix flake support

[leomeowqq]

Adds a minimal Nix flake so torrra can be used on NixOS without manual building.

Closes discussion #49.

What's included

• flake.nix - standard flake with packages, overlay, and NixOS module
• package.nix - buildGoModule derivation for torrra

Usage after merge

# run directly
nix run github:stabldev/torrra

Or add to your NixOS configuration:

# In flake.nix inputs
torrra.url = "github:stabldev/torrra";

# In your NixOS configuration
environment.systemPackages = [ inputs.torrra.packages.${pkgs.system}.default ];

Tested on NixOS (x86_64-linux).

[stabldev]

hey @leoxyeo
thank you for this PR. looks good, just one thing- can you move the nix installation guide to this docs file: https://github.com/stabldev/torrra/edit/main/docs/installation.md

[leomeowqq]

hey @leoxyeo
thank you for this PR. looks good, just one thing- can you move the nix installation guide to this docs file: https://github.com/stabldev/torrra/edit/main/docs/installation.md

sure I can :) no problem, give me a minute

[stabldev]

thank you @leomeowqq !
merging...