GHSA-4VH2-39RQ-RQ8J Vikunja: Unbounded image decode on avatar and project-background uploads enables decode/resize amplification

Summary The 50-megapixel decode guard exists only on the task-attachment preview path. Avatar and project-background uploads decode uploaded images with no pixel cap. Worse, the avatar resize fixes the output height at 1024 and derives the width from the aspect ratio, so a tiny extreme-aspect-rat...