add lock merge strategy

nixos/common/hm-modules/default.nix

@@ -1 +1,3 @@
-{ ... }: { imports = [ ./catppuccin.nix ./nvim.nix ./riff.nix ./vscode.nix ]; }
+{ ... }: {
+  imports = [ ./catppuccin.nix ./nvim.nix ./riff.nix ./vscode.nix ./git.nix ];
+}

nixos/common/hm-modules/git.nix

@@ -0,0 +1,31 @@
+{ config, pkgs, lib, ... }:
+with lib;
+let cfg = config.programs.v.git;
+in {
+  options.programs.v.git = { enable = mkEnableOption "git"; };
+  config = mkIf cfg.enable {
+    programs.git = {
+      enable = true;
+      package = pkgs.gitAndTools.gitFull;
+      userName = "Victor";
+      userEmail = "victor@xirion.net";
+      lfs.enable = true;
+      extraConfig = {
+        push.autoSetupRemote = true;
+        init.defaultBranch = "main";
+        # Git merge driver that always grabs upstream changes
+        # Useful for e.g. lock files
+        merge.theirs = {
+          name = "Keep Upstream Changes";
+          driver = "cp -f '%B' '%A'";
+        };
+      };
+
+      difftastic.enable = true;
+    };
+
+    home.file.".config/git/attributes".text = ''
+      flake.lock merge=theirs
+    '';
+  };
+}