renderer: uncomment resize message handling

We need this to get info about the padding, even if we do derive the
grid and screen size separately.

In the future this should possibly be changed to a message that only
sends the padding info and nothing else.

src/renderer/Thread.zig

@@ -452,7 +452,7 @@ fn drainMailbox(self: *Thread) !void {
                 self.renderer.markDirty();
             },
 
-            .resize => {}, //|v| try self.renderer.setScreenSize(v),
+            .resize => |v| self.renderer.setScreenSize(v),
 
             .change_config => |config| {
                 defer config.alloc.destroy(config.thread);