- Add glm-5.1 model to GLM Coding provider with fitness scores
- Update glm-5 pricing to match Z.AI API page ($1/$3.2/$0.2)
- Set glm-5.1 pricing to $1.2/$5/$0.3 per Z.AI
- Remove glm-4-32b (deprecated, returns empty from upstream)
- Rename Z.AI provider display name from "Z.AI (GLM-5)" to "Z.AI"
- Update zai pricing section to match glm pricing