mach: begin unified entry point interface

src/entry/native.zig

@@ -0,0 +1,12 @@
+const app = @import("app");
+
+pub fn main() !void {
+    try app.init();
+    defer app.deinit();
+
+    while (true) {
+        const success = try app.update();
+        if (!success)
+            break;
+    }
+}