feat: add admin user edit page with avatar, banner, and photo gallery

- Backend: adminGetUser query returns user + photos; adminUpdateUser now
  accepts avatarId/bannerId; new adminAddUserPhoto and adminRemoveUserPhoto
  mutations; AdminUserDetailType added to GraphQL schema
- Frontend: /admin/users/[id] page for editing name, avatar, banner, and
  managing the model photo gallery (upload multiple, delete individually)
- Admin users list: edit button per row linking to the detail page

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

packages/frontend/src/lib/services.ts

@@ -1055,6 +1055,8 @@ const ADMIN_UPDATE_USER_MUTATION = gql`
     $firstName: String
     $lastName: String
     $artistName: String
+    $avatarId: String
+    $bannerId: String
   ) {
     adminUpdateUser(
       userId: $userId
@@ -1062,6 +1064,8 @@ const ADMIN_UPDATE_USER_MUTATION = gql`
       firstName: $firstName
       lastName: $lastName
       artistName: $artistName
+      avatarId: $avatarId
+      bannerId: $bannerId
     ) {
       id
       email
@@ -1070,6 +1074,7 @@ const ADMIN_UPDATE_USER_MUTATION = gql`
       artist_name
       role
       avatar
+      banner
       date_created
     }
   }
@@ -1081,6 +1086,8 @@ export async function adminUpdateUser(input: {
   firstName?: string;
   lastName?: string;
   artistName?: string;
+  avatarId?: string;
+  bannerId?: string;
 }) {
   return loggedApiCall(
     "adminUpdateUser",
@@ -1111,6 +1118,66 @@ export async function adminDeleteUser(userId: string) {
   );
 }
 
+const ADMIN_GET_USER_QUERY = gql`
+  query AdminGetUser($userId: String!) {
+    adminGetUser(userId: $userId) {
+      id
+      email
+      first_name
+      last_name
+      artist_name
+      slug
+      role
+      avatar
+      banner
+      description
+      tags
+      email_verified
+      date_created
+      photos {
+        id
+        filename
+      }
+    }
+  }
+`;
+
+export async function adminGetUser(userId: string, token?: string) {
+  return loggedApiCall(
+    "adminGetUser",
+    async () => {
+      const client = token ? getAuthClient(token) : getGraphQLClient();
+      const data = await client.request<{ adminGetUser: any }>(ADMIN_GET_USER_QUERY, { userId });
+      return data.adminGetUser;
+    },
+    { userId },
+  );
+}
+
+const ADMIN_ADD_USER_PHOTO_MUTATION = gql`
+  mutation AdminAddUserPhoto($userId: String!, $fileId: String!) {
+    adminAddUserPhoto(userId: $userId, fileId: $fileId)
+  }
+`;
+
+export async function adminAddUserPhoto(userId: string, fileId: string) {
+  return loggedApiCall("adminAddUserPhoto", async () => {
+    await getGraphQLClient().request(ADMIN_ADD_USER_PHOTO_MUTATION, { userId, fileId });
+  });
+}
+
+const ADMIN_REMOVE_USER_PHOTO_MUTATION = gql`
+  mutation AdminRemoveUserPhoto($userId: String!, $fileId: String!) {
+    adminRemoveUserPhoto(userId: $userId, fileId: $fileId)
+  }
+`;
+
+export async function adminRemoveUserPhoto(userId: string, fileId: string) {
+  return loggedApiCall("adminRemoveUserPhoto", async () => {
+    await getGraphQLClient().request(ADMIN_REMOVE_USER_PHOTO_MUTATION, { userId, fileId });
+  });
+}
+
 // ─── Admin: Videos ────────────────────────────────────────────────────────────
 
 const ADMIN_LIST_VIDEOS_QUERY = gql`