Add explicit toJSON() method to queries

allows for e.g.:

const articles = await Article.with("user").orderBy("createdAt", "desc").toJSON();

from a loader to explicitly return the serialized version of a model to provide it to a component. this makes it so that the version of the model that is provided during SSR is exactly equivalent to the version of the model that is made available to the component when rendered on the client. otherwise, the data made available to the component during SSR when using single fetch is the actual model instance.

packages/superflare/src/query-builder.ts

@@ -10,6 +10,7 @@ export class QueryBuilder {
   private $eagerLoad: string[] = [];
   private $limit: number | null = null;
   private $single: boolean = false;
+  private $serialize: boolean = false;
   private $modelClass: any;
   private $afterHooks: ((results: any) => void)[] = [];
 
@@ -69,6 +70,9 @@ export class QueryBuilder {
 
       results = await this.eagerLoadRelations(results);
 
+      results = this.$serialize
+        ? results.map((result: typeof this.$modelClass) => result.toJSON())
+        : results;
       let result = this.$single ? results[0] ?? null : results;
 
       this.runCallbacks(result);
@@ -139,6 +143,11 @@ export class QueryBuilder {
     return this.limit(1);
   }
 
+  toJSON(): this {
+    this.$serialize = true;
+    return this;
+  }
+
   async insert(attributes: Record<string, any>): Promise<any> {
     try {
       const results = await this.connection()