fix(index): align google provider startup check to use GEMINI_API_KEY (#63)

Author: Nivesh353

src/index.ts

@@ -512,7 +512,7 @@ async function main(): Promise<void> {
 	const apiKeyEnvVars: Record<string, string> = {
 		anthropic: "ANTHROPIC_API_KEY",
 		openai: "OPENAI_API_KEY",
-		google: "GOOGLE_API_KEY",
+		google: "GEMINI_API_KEY",
 		xai: "XAI_API_KEY",
 		groq: "GROQ_API_KEY",
 		mistral: "MISTRAL_API_KEY",