Implement provider formatting improvements and fix client-side compatibility

- Add PROVIDER_INFO metadata to each provider file with proper display names
- Create centralized PROVIDER_METADATA in index.ts for consistent reference
- Update settings UI to use provider metadata for display names
- Fix client/server compatibility for Node.js modules in config.ts

src/lib/providers/gemini.ts

@@ -4,6 +4,11 @@ import {
 } from '@langchain/google-genai';
 import { getGeminiApiKey } from '../config';
 import { ChatModel, EmbeddingModel } from '.';
+
+export const PROVIDER_INFO = {
+  key: 'gemini',
+  displayName: 'Google Gemini'
+};
 import { BaseChatModel } from '@langchain/core/language_models/chat_models';
 import { Embeddings } from '@langchain/core/embeddings';