renderer/metal: detect frame commit failures and notify surface

src/renderer.zig

@@ -52,6 +52,14 @@ pub const Renderer = switch (build_config.renderer) {
     .webgl => WebGL,
 };
 
+/// The health status of a renderer. These must be shared across all
+/// renderers even if some states aren't reachable so that our API users
+/// can use the same enum for all renderers.
+pub const Health = enum(u8) {
+    healthy = 0,
+    unhealthy = 1,
+};
+
 test {
     @import("std").testing.refAllDecls(@This());
 }