Add database-backed bookmarks via GraphQL

Replace hardcoded bookmarks in the frontend with a GORM-backed Bookmark
model exposed through GraphQL query and admin-only create/delete mutations.
Frontend groups bookmarks by category dynamically from the store.

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

backend/graph/bookmark.resolvers.go

@@ -0,0 +1,22 @@
+package graph
+
+// This file will be automatically regenerated based on the schema, any resolver
+// implementations
+// will be copied through when generating and any unknown code will be moved to the end.
+// Code generated by github.com/99designs/gqlgen version v0.17.88
+
+import (
+	"context"
+
+	"adam-french.co.uk/backend/models"
+)
+
+// ID is the resolver for the id field.
+func (r *bookmarkResolver) ID(ctx context.Context, obj *models.Bookmark) (int, error) {
+	return int(obj.ID), nil
+}
+
+// Bookmark returns BookmarkResolver implementation.
+func (r *Resolver) Bookmark() BookmarkResolver { return &bookmarkResolver{r} }
+
+type bookmarkResolver struct{ *Resolver }