fix nix profile deprecation warning on install: use 'nix profile add' (current verb) instead of 'nix profile install' (deprecated alias that prints a warning on modern nix); updated the command echo + teach text to match — build+tests green

@@ -607,8 +607,8 @@607607 608608 fn profileInstallPkg(ctx: Ctx, npkg: types.NixPackage) !void {609609     output.installStart(npkg.pname, .profile);610-    output.printSubstep("nix profile install nixpkgs#{s}", .{npkg.attr});611-    output.printTeach(try std.fmt.allocPrint(ctx.gpa, "nix profile install nixpkgs#{s}", .{npkg.attr}));610+    output.printSubstep("nix profile add nixpkgs#{s}", .{npkg.attr});611+    output.printTeach(try std.fmt.allocPrint(ctx.gpa, "nix profile add nixpkgs#{s}", .{npkg.attr}));612612     const code = try exec.profileInstall(ctx.io, &ctx.machine, ctx.gpa, npkg.attr);613613     if (code != 0) return error.ProcessFailed;614614     output.installDone(npkg.pname);

@@ -330,7 +330,9 @@330330 pub fn profileInstall(io: std.Io, machine: *const types.Machine, gpa: std.mem.Allocator, attr: []const u8) !u8 {331331     const pkg_ref = try std.fmt.allocPrint(gpa, "nixpkgs#{s}", .{attr});332332     defer gpa.free(pkg_ref);333-    return stream(io, machine, gpa, &.{ "nix", "profile", "install", pkg_ref });333+    // `nix profile add` is the current verb; `install` is a deprecated alias that334+    // prints a warning on modern nix.335+    return stream(io, machine, gpa, &.{ "nix", "profile", "add", pkg_ref });334336 }335337 336338 pub fn profileRemove(io: std.Io, machine: *const types.Machine, gpa: std.mem.Allocator, attr: []const u8) !u8 {