Bitesize Reading Library V4.9.10 — Resource Thumbnails & YouTube Links

- Larger, uncropped resource thumbnails in Next Reading Step, More for this Topic and Recommended Reading panels.
- Covers use object-fit: contain rather than narrow cropped strips.
- Improved topic detection from resource titles and verified catalogue metadata.
- Fossil Main Idea Escape Room now links directly to Bitesize Education: How Are Fossils Made? (YouTube video ug797fB4IGE).
- Separate topic and comprehension-skill searches on Bitesize Education YouTube channel.
- Offline curated video fallback when live videos.json has not been updated.
- Existing bonus, standards, edition label and Discover fixes retained.
