🔑 [feat] Add Gemini API key support

- Include Gemini API key in the getAPIKey function
- Allow retrieval of Gemini API key from environment variables

app/lib/.server/llm/api-key.ts

@@ -16,6 +16,8 @@ export function getAPIKey(cloudflareEnv: Env, provider: string) {
       return env.GROQ_API_KEY || cloudflareEnv.GROQ_API_KEY;
     case 'OpenRouter':
       return env.OPEN_ROUTER_API_KEY || cloudflareEnv.OPEN_ROUTER_API_KEY;
+    case 'Gemini':
+      return env.GEMINI_API_KEY || cloudflareEnv.GEMINI_API_KEY;
     // AWS credentials for Bedrock are obtained separately
     default:
       return "";