Fix Claude Sonnet 4 model ID (#31505)

This PR is a follow-up to
https://github.com/zed-industries/zed/pull/31415 that fixes the model ID
for Claude Sonnet 4.

With the release of the Claude 4 models, the model version now appears
at the end.

Release Notes:

- N/A

docs/src/configuring-zed.md

@@ -3287,11 +3287,11 @@ Run the `theme selector: toggle` action in the command palette to see a current
   "default_view": "thread",
   "default_model": {
     "provider": "zed.dev",
-    "model": "claude-4-sonnet"
+    "model": "claude-sonnet-4"
   },
   "editor_model": {
     "provider": "zed.dev",
-    "model": "claude-4-sonnet"
+    "model": "claude-sonnet-4"
   },
   "single_file_review": true,
 }