feat: add config

.env.example

@@ -0,0 +1 @@
+OPENROUTER_API_KEY=

src/config.ts

@@ -0,0 +1,12 @@
+import "dotenv/config";
+
+export interface Config {
+  openrouterApiKey: string;
+}
+
+const openrouterApiKey = process.env["OPENROUTER_API_KEY"];
+if (!openrouterApiKey) throw new Error("OPENROUTER_API_KEY is missing");
+
+export const config: Config = {
+  openrouterApiKey: openrouterApiKey,
+};