feat (provider/perplexity): add sonar-deep-research model (#5996)

## Background

New perplexity model `sonar-deep-research` is available.

## Summary

Add sonar-deep-research model id to perplexity provider.

## Verification

Ran generation using `sonar-deep-research`

---------

Co-authored-by: Lars Grammel <[email protected]>

Author: jhsu

.changeset/famous-eggs-camp.md

@@ -0,0 +1,5 @@
+---
+'@ai-sdk/perplexity': patch
+---
+
+feat (provider/perplexity): add sonar-deep-research model

README.md

@@ -1 +1 @@
-packages/ai/README.md
+packages/ai/README.md

content/providers/01-ai-sdk-providers/70-perplexity.mdx

@@ -136,10 +136,11 @@ You can enable image responses by setting `return_images: true` in the provider
 
 ## Model Capabilities
 
-| Model       | Image Input         | Object Generation   | Tool Usage          | Tool Streaming      |
-| ----------- | ------------------- | ------------------- | ------------------- | ------------------- |
-| `sonar-pro` | <Cross size={18} /> | <Cross size={18} /> | <Cross size={18} /> | <Cross size={18} /> |
-| `sonar`     | <Cross size={18} /> | <Cross size={18} /> | <Cross size={18} /> | <Cross size={18} /> |
+| Model                 | Image Input         | Object Generation   | Tool Usage          | Tool Streaming      |
+| --------------------- | ------------------- | ------------------- | ------------------- | ------------------- |
+| `sonar-pro`           | <Cross size={18} /> | <Cross size={18} /> | <Cross size={18} /> | <Cross size={18} /> |
+| `sonar`               | <Cross size={18} /> | <Cross size={18} /> | <Cross size={18} /> | <Cross size={18} /> |
+| `sonar-deep-research` | <Cross size={18} /> | <Cross size={18} /> | <Cross size={18} /> | <Cross size={18} /> |
 
 <Note>
   Please see the [Perplexity docs](https://docs.perplexity.ai) for detailed API

packages/perplexity/src/perplexity-language-model-settings.ts

@@ -1,5 +1,6 @@
-// https://docs.perplexity.ai/guides/model-cards
+// https://docs.perplexity.ai/models/model-cards
 export type PerplexityLanguageModelId =
+  | 'sonar-deep-research'
   | 'sonar-reasoning-pro'
   | 'sonar-reasoning'
   | 'sonar-pro'