upgrade: live build panel during rebuild phase

@@ -573,8 +573,14 @@573573         _ = exec.channelUpdate(ctx.io, &ctx.machine, ctx.gpa) catch {};574574     }575575     output.printSubstep("rebuilding", .{});576+    output.buildPanelInit();576577     const start = std.Io.Clock.awake.now(ctx.io);577-    const code = try exec.nixosRebuildSwitch(ctx.io, &ctx.machine, ctx.gpa);578+    var panel = output.BuildPanel{};579+    const code = exec.nixosRebuildSwitchWithPanel(ctx.io, &ctx.machine, ctx.gpa, &panel) catch |e| {580+        output.buildPanelClear();581+        return e;582+    };583+    output.buildPanelClear();578584     if (code != 0) {579585         output.applyFailed("");580586         return error.BuildFailed;