feat(server): extract check params (#12187)

<!-- This is an auto-generated comment: release notes by coderabbit.ai -->
## Summary by CodeRabbit

- **New Features**
  - Improved input validation and error reporting for chat messages, attachments, and embeddings, with clearer error messages for invalid inputs.
  - Enhanced support for multimodal messages, including attachments such as images or audio.

- **Refactor**
  - Unified and streamlined parameter validation across AI providers, resulting in more consistent behavior and error handling.
  - Centralized parameter checks into a common provider layer, removing duplicate validation code from individual AI providers.

- **Tests**
  - Simplified and consolidated audio transcription test stubs for better maintainability.
<!-- end of auto-generated comment: release notes by coderabbit.ai -->

packages/backend/server/src/plugins/copilot/providers/perplexity.ts

@@ -5,17 +5,12 @@ import {
 import { generateText, streamText } from 'ai';
 import { z } from 'zod';
 
-import {
-  CopilotPromptInvalid,
-  CopilotProviderSideError,
-  metrics,
-} from '../../../base';
+import { CopilotProviderSideError, metrics } from '../../../base';
 import { CopilotProvider } from './provider';
 import {
   CopilotChatOptions,
   CopilotProviderType,
   ModelConditions,
-  ModelFullConditions,
   ModelInputType,
   ModelOutputType,
   PromptMessage,
@@ -115,7 +110,7 @@ export class PerplexityProvider extends CopilotProvider<PerplexityConfig> {
     options: CopilotChatOptions = {}
   ): Promise<string> {
     const fullCond = { ...cond, outputType: ModelOutputType.Text };
-    await this.checkParams({ cond: fullCond, messages });
+    await this.checkParams({ cond: fullCond, messages, options });
     const model = this.selectModel(fullCond);
 
     try {
@@ -155,7 +150,7 @@ export class PerplexityProvider extends CopilotProvider<PerplexityConfig> {
     options: CopilotChatOptions = {}
   ): AsyncIterable<string> {
     const fullCond = { ...cond, outputType: ModelOutputType.Text };
-    await this.checkParams({ cond: fullCond, messages });
+    await this.checkParams({ cond: fullCond, messages, options });
     const model = this.selectModel(fullCond);
 
     try {
@@ -215,19 +210,6 @@ export class PerplexityProvider extends CopilotProvider<PerplexityConfig> {
     }
   }
 
-  protected async checkParams({
-    cond,
-  }: {
-    cond: ModelFullConditions;
-    messages?: PromptMessage[];
-    embeddings?: string[];
-    options?: CopilotChatOptions;
-  }) {
-    if (!(await this.match(cond))) {
-      throw new CopilotPromptInvalid(`Invalid model: ${cond.modelId}`);
-    }
-  }
-
   private convertError(e: PerplexityError) {
     function getErrMessage(e: PerplexityError) {
       let err = 'Unexpected perplexity response';