Massively simplify API binding logic

Changes the API internals to use normal Laravel binding which automatically supports nested-models and can determine their relationships. This removes a lot of confusingly complex internal logic and replaces it with standard Laravel code.

This also removes a deprecated "getModel" method and fully replaces it with a "parameter" method that does stricter type-checking.

app/Models/Model.php

@@ -68,6 +68,20 @@ abstract class Model extends IlluminateModel
         });
     }
 
+    /**
+     * Returns the model key to use for route model binding. By default we'll
+     * assume every model uses a UUID field for this. If the model does not have
+     * a UUID and is using a different key it should be specified on the model
+     * itself.
+     *
+     * You may also optionally override this on a per-route basis by declaring
+     * the key name in the URL definition, like "{user:id}".
+     */
+    public function getRouteKeyName(): string
+    {
+        return 'uuid';
+    }
+
     /**
      * Set the model to skip validation when saving.
      *