feat: add support for DouBao, Ernie, Kimi, Qwen, ZhiPu LLM providers

Introduces new provider modules for DouBao, Ernie, Kimi, Qwen, and ZhiPu, and registers them in the LLM registry. Updates documentation and .env.example to include configuration instructions for these providers. Refactors OpenAI provider to support OpenAI-compatible endpoints. Adds @ai-sdk/openai-compatible and node-fetch dependencies.

app/lib/modules/llm/registry.ts

@@ -2,24 +2,34 @@ import AmazonBedrockProvider from './providers/amazon-bedrock';
 import AnthropicProvider from './providers/anthropic';
 import CohereProvider from './providers/cohere';
 import DeepseekProvider from './providers/deepseek';
+import DouBaoProvider from './providers/doubao';
+import ErnieProvider from './providers/ernie';
 import GithubProvider from './providers/github';
 import GoogleProvider from './providers/google';
 import GroqProvider from './providers/groq';
 import HuggingFaceProvider from './providers/huggingface';
 import HyperbolicProvider from './providers/hyperbolic';
+import KimiProvider from './providers/kimi';
 import LMStudioProvider from './providers/lmstudio';
 import MistralProvider from './providers/mistral';
 import OllamaProvider from './providers/ollama';
 import OpenRouterProvider from './providers/open-router';
 import OpenAIProvider from './providers/openai';
 import PerplexityProvider from './providers/perplexity';
+import QwenProvider from './providers/qwen';
 import TogetherProvider from './providers/together';
 import XAIProvider from './providers/xai';
+import ZhiPuProvider from './providers/zhipu';
 
 export {
   AnthropicProvider,
   CohereProvider,
   DeepseekProvider,
+  DouBaoProvider,
+  ErnieProvider,
+  KimiProvider,
+  QwenProvider,
+  ZhiPuProvider,
   GoogleProvider,
   GroqProvider,
   HuggingFaceProvider,