zen: add gpt5.1 to docs

Author: Frank

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

@@ -64,6 +64,8 @@ You can also access our models through the following API endpoints.
 
 | Model             | Model ID          | Endpoint                                      | AI SDK Package              |
 | ----------------- | ----------------- | --------------------------------------------- | --------------------------- |
+| GPT 5.1           | gpt-5.1           | `https://opencode.ai/zen/v1/responses`        | `@ai-sdk/openai`            |
+| GPT 5.1 Codex     | gpt-5.1-codex     | `https://opencode.ai/zen/v1/responses`        | `@ai-sdk/openai`            |
 | GPT 5             | gpt-5             | `https://opencode.ai/zen/v1/responses`        | `@ai-sdk/openai`            |
 | GPT 5 Codex       | gpt-5-codex       | `https://opencode.ai/zen/v1/responses`        | `@ai-sdk/openai`            |
 | Claude Sonnet 4.5 | claude-sonnet-4-5 | `https://opencode.ai/zen/v1/messages`         | `@ai-sdk/anthropic`         |
@@ -78,8 +80,8 @@ You can also access our models through the following API endpoints.
 | Big Pickle        | big-pickle        | `https://opencode.ai/zen/v1/chat/completions` | `@ai-sdk/openai-compatible` |
 
 The [model id](/docs/config/#models) in your OpenCode config
-uses the format `opencode/<model-id>`. For example, for GPT 5 Codex, you would
-use `opencode/gpt-5-codex` in your config.
+uses the format `opencode/<model-id>`. For example, for GPT 5.1 Codex, you would
+use `opencode/gpt-5.1-codex` in your config.
 
 ---
 
@@ -127,6 +129,8 @@ We support a pay-as-you-go model. Below are the prices **per 1M tokens**.
 | Claude Haiku 4.5                  | $1.00  | $5.00  | $0.10       | $1.25        |
 | Claude Haiku 3.5                  | $0.80  | $4.00  | $0.08       | $1.00        |
 | Claude Opus 4.1                   | $15.00 | $75.00 | $1.50       | $18.75       |
+| GPT 5.1                           | $1.25  | $10.00 | $0.125      | -            |
+| GPT 5.1 Codex                     | $1.25  | $10.00 | $0.125      | -            |
 | GPT 5                             | $1.25  | $10.00 | $0.125      | -            |
 | GPT 5 Codex                       | $1.25  | $10.00 | $0.125      | -            |