feat(providers): Add vision and document processing capabilities to providers

ts/provider.perplexity.ts

@@ -155,4 +155,17 @@ export class PerplexityProvider extends MultiModalModel {
   public async audio(optionsArg: { message: string }): Promise<NodeJS.ReadableStream> {
     throw new Error('Audio generation is not supported by Perplexity.');
   }
+
+  public async vision(optionsArg: { image: Buffer; prompt: string }): Promise<string> {
+    throw new Error('Vision tasks are not supported by Perplexity.');
+  }
+
+  public async document(optionsArg: {
+    systemMessage: string;
+    userMessage: string;
+    pdfDocuments: Uint8Array[];
+    messageHistory: ChatMessage[];
+  }): Promise<{ message: any }> {
+    throw new Error('Document processing is not supported by Perplexity.');
+  }
 }