move au into nu/render

src/App.zig

@@ -1,11 +1,8 @@
 const std = @import("std");
 const nu = @import("nu.zig");
 
-const Self = @This();
-
 pub fn init(alloc: std.mem.Allocator) !void {
     _ = alloc;
 }
 
-pub fn deinit() void {
-}
+pub fn deinit() void {}