📦 feat(git): add radicle package

- add `radicle` package
- add `radicle-tui` package
- create fish alias for `rad-tui`
- add radicle config template `radicle.nix`
- add `.gitconfig.radicle` to `.gitconfig`
- create directory for radicle projects with its `.gitconfig.radicle`

nixos/radicle.nix

@@ -0,0 +1,13 @@
+{ inputs, pkgs, ... }:
+
+{
+  services.radicle = {
+    enable = false;
+    checkConfig = false;
+  };
+
+  environment.systemPackages = with pkgs; [
+    inputs.radicle-tui.packages.${pkgs.system}.default
+    radicle-node
+  ];
+}