fix: add adminGetVideo/adminGetArticle queries to fix 404 on edit pages

The edit page loaders were calling adminListVideos/adminListArticles with the
old pre-pagination signatures and filtering by ID client-side, which broke
after pagination limited results to 50. Now fetches the single item by ID
directly via new adminGetVideo and adminGetArticle backend queries.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

packages/frontend/src/lib/services.ts

@@ -1339,6 +1339,51 @@ export async function adminListVideos(
   });
 }
 
+const ADMIN_GET_VIDEO_QUERY = gql`
+  query AdminGetVideo($id: String!) {
+    adminGetVideo(id: $id) {
+      id
+      slug
+      title
+      description
+      image
+      movie
+      tags
+      upload_date
+      premium
+      featured
+      likes_count
+      plays_count
+      models {
+        id
+        artist_name
+        slug
+        avatar
+      }
+      movie_file {
+        id
+        filename
+        mime_type
+        duration
+      }
+    }
+  }
+`;
+
+export async function adminGetVideo(
+  id: string,
+  fetchFn?: typeof globalThis.fetch,
+  token?: string,
+): Promise<Video | null> {
+  return loggedApiCall("adminGetVideo", async () => {
+    const client = token ? getAuthClient(token) : getGraphQLClient(fetchFn);
+    const data = await client.request<{ adminGetVideo: Video | null }>(ADMIN_GET_VIDEO_QUERY, {
+      id,
+    });
+    return data.adminGetVideo;
+  });
+}
+
 const CREATE_VIDEO_MUTATION = gql`
   mutation CreateVideo(
     $title: String!
@@ -1543,6 +1588,44 @@ export async function adminListArticles(
   });
 }
 
+const ADMIN_GET_ARTICLE_QUERY = gql`
+  query AdminGetArticle($id: String!) {
+    adminGetArticle(id: $id) {
+      id
+      slug
+      title
+      excerpt
+      content
+      image
+      tags
+      publish_date
+      category
+      featured
+      author {
+        id
+        artist_name
+        slug
+        avatar
+      }
+    }
+  }
+`;
+
+export async function adminGetArticle(
+  id: string,
+  fetchFn?: typeof globalThis.fetch,
+  token?: string,
+): Promise<Article | null> {
+  return loggedApiCall("adminGetArticle", async () => {
+    const client = token ? getAuthClient(token) : getGraphQLClient(fetchFn);
+    const data = await client.request<{ adminGetArticle: Article | null }>(
+      ADMIN_GET_ARTICLE_QUERY,
+      { id },
+    );
+    return data.adminGetArticle;
+  });
+}
+
 const CREATE_ARTICLE_MUTATION = gql`
   mutation CreateArticle(
     $title: String!