Support GLM coding plan

Author: Frank

packages/web/src/content/docs/providers.mdx

@@ -745,6 +745,19 @@ monitor and improve Grok Code.
    └
    ```
 
+   If you are subscribed to the **GLM Coding Plan**, select **Z.AI Coding Plan**.
+
+   ```bash
+   $ opencode auth login
+
+   ┌  Add credential
+   │
+   ◆  Select provider
+   │  ● Z.AI Coding Plan
+   │  ...
+   └
+   ```
+
 3. Enter your Z.AI API key.
 
    ```bash