Finished the Grok LLM implementation

lib/llm/index.mjs

@@ -7,6 +7,7 @@ import { GeminiProvider } from './gemini.mjs';
 import { CodexProvider } from './codex.mjs';
 import { MiniMaxProvider } from './minimax.mjs';
 import { MistralProvider } from './mistral.mjs';
+import { GrokProvider } from './grok.mjs';
 
 export { LLMProvider } from './provider.mjs';
 export { AnthropicProvider } from './anthropic.mjs';
@@ -16,6 +17,8 @@ export { GeminiProvider } from './gemini.mjs';
 export { CodexProvider } from './codex.mjs';
 export { MiniMaxProvider } from './minimax.mjs';
 export { MistralProvider } from './mistral.mjs';
+export { GrokProvider } from './grok.mjs';
+
 
 /**
  * Create an LLM provider based on config.
@@ -42,6 +45,8 @@ export function createLLMProvider(llmConfig) {
       return new MiniMaxProvider({ apiKey, model });
     case 'mistral':
       return new MistralProvider({ apiKey, model });
+    case 'grok':
+      return new GrokProvider({ apiKey, model });
     default:
       console.warn(`[LLM] Unknown provider "${provider}". LLM features disabled.`);
       return null;