feat(llm): GLM dual-region split + catalog refresh

Zhipu serves GLM under two brands with separate accounts (Z.AI
international vs BigModel China); the CLI URL pointed at one while
the openai_client default pointed at the other. Split into glm +
glm-cn with secondary region prompt (same UX as Qwen + MiniMax).
Catalog adds glm-5-turbo and glm-4.5-air per docs.z.ai.

.env.example

@@ -5,7 +5,9 @@ ANTHROPIC_API_KEY=
 XAI_API_KEY=
 DEEPSEEK_API_KEY=
 DASHSCOPE_API_KEY=
+DASHSCOPE_CN_API_KEY=
 ZHIPU_API_KEY=
+ZHIPU_CN_API_KEY=
 MINIMAX_API_KEY=
 MINIMAX_CN_API_KEY=
 OPENROUTER_API_KEY=