fix(provider): auto-enable interleaved for reasoning models on @ai-sdk/openai-compatible

When a user configures a model with reasoning: true but doesn't explicitly
set interleaved, the default was false. This caused reasoning_content to be
dropped during message replay for @ai-sdk/openai-compatible users.

Now, if reasoning: true is configured and interleaved is not explicitly set,
it defaults to { field: "reasoning_content" } instead of false.

Author: fkyah3

packages/opencode/src/provider/provider.ts

@@ -1177,7 +1177,7 @@ const layer: Layer.Layer<
                     model.modalities?.output?.includes("video") ?? existingModel?.capabilities.output.video ?? false,
                   pdf: model.modalities?.output?.includes("pdf") ?? existingModel?.capabilities.output.pdf ?? false,
                 },
-                interleaved: model.interleaved ?? existingModel?.capabilities.interleaved ?? false,
+                interleaved: model.interleaved ?? existingModel?.capabilities.interleaved ?? (model.reasoning ? { field: "reasoning_content" } : false),
               },
               cost: {
                 input: model?.cost?.input ?? existingModel?.cost?.input ?? 0,