feat: add shared collection page

app/controllers/shared_collections_controller.ts

@@ -0,0 +1,24 @@
+import { Visibility } from '#enums/visibility';
+import Collection from '#models/collection';
+import { getSharedCollectionValidator } from '#validators/shared_collection';
+import type { HttpContext } from '@adonisjs/core/http';
+
+export default class SharedCollectionsController {
+  async index({ request, inertia }: HttpContext) {
+    const { params } = await request.validateUsing(
+      getSharedCollectionValidator
+    );
+
+    const collection = await this.getSharedCollectionById(params.id);
+    return inertia.render('shared', { collection });
+  }
+
+  private async getSharedCollectionById(id: Collection['id']) {
+    return await Collection.query()
+      .where('id', id)
+      .andWhere('visibility', Visibility.PUBLIC)
+      .preload('links')
+      .preload('author')
+      .firstOrFail();
+  }
+}