feat(research): Introduce research API with provider implementations, docs and tests

ts/provider.xai.ts

@@ -1,7 +1,7 @@
 import * as plugins from './plugins.js';
 import * as paths from './paths.js';
 import { MultiModalModel } from './abstract.classes.multimodal.js';
-import type { ChatOptions, ChatResponse, ChatMessage } from './abstract.classes.multimodal.js';
+import type { ChatOptions, ChatResponse, ChatMessage, ResearchOptions, ResearchResponse } from './abstract.classes.multimodal.js';
 import type { ChatCompletionMessageParam } from 'openai/resources/chat/completions';
 
 export interface IXAIProviderOptions {
@@ -181,4 +181,8 @@ export class XAIProvider extends MultiModalModel {
       message: completion.choices[0]?.message?.content || ''
     };
   }
+
+  public async research(optionsArg: ResearchOptions): Promise<ResearchResponse> {
+    throw new Error('Research capabilities are not yet supported by xAI provider.');
+  }
 }