feat: add OpenRouter audit generation pipeline

lib/ai/openrouter-provider.ts

@@ -0,0 +1,35 @@
+import { createOpenRouter } from "@openrouter/ai-sdk-provider";
+
+type OpenRouterEnv = Readonly<Record<string, string | undefined>>;
+
+function normalizeOptionalEnvValue(value: string | undefined): string | undefined {
+  if (typeof value !== "string") {
+    return undefined;
+  }
+
+  const trimmed = value.trim();
+  return trimmed === "" ? undefined : trimmed;
+}
+
+export function createOpenRouterProvider(
+  env: OpenRouterEnv = process.env,
+): ReturnType<typeof createOpenRouter> {
+  const apiKey = normalizeOptionalEnvValue(env.OPENROUTER_API_KEY);
+
+  if (!apiKey) {
+    throw new Error("OPENROUTER_API_KEY is required for OpenRouter provider.");
+  }
+
+  const appName = normalizeOptionalEnvValue(env.OPENROUTER_APP_NAME);
+  const appUrl = normalizeOptionalEnvValue(env.OPENROUTER_APP_URL);
+
+  return createOpenRouter({
+    apiKey,
+    appName,
+    appUrl,
+    compatibility: "strict",
+    headers: {
+      "Content-Type": "application/json",
+    },
+  });
+}