Add four distinct provider variants for GLM models:
- zai: International pay-as-you-go (api.z.ai)
- zai-coding: International Coding Plan (api.z.ai/coding)
- zhipu: China pay-as-you-go (bigmodel.cn)
- zhipu-coding: China Coding Plan (bigmodel.cn/coding)
Includes:
- Provider config functions with proper base URLs
- GLM model definition (glm-4.7, 205K context)
- Env var resolution with fallback chains
- Provider ID normalization for aliases
- Usage provider IDs and labels
Generated with [Claude Code](https://claude.ai/code)
via [Happy](https://happy.engineering)
Co-Authored-By: Claude <noreply@anthropic.com>
Co-Authored-By: Happy <yesreply@happy.engineering>
