feat: add api key validation endpoint and update comic generation model

app/api/validate-api-key/route.ts

@@ -0,0 +1,45 @@
+import { type NextRequest, NextResponse } from "next/server";
+import Together from "together-ai";
+
+export async function POST(request: NextRequest) {
+  try {
+    const { apiKey } = await request.json();
+
+    if (!apiKey || typeof apiKey !== "string") {
+      return NextResponse.json(
+        { valid: false, error: "API key is required" },
+        { status: 400 },
+      );
+    }
+
+    // Dynamically fetch the fastest available model
+    const routerRes = await fetch("https://whichllm.together.ai/router/fast", {
+      next: { revalidate: 60 },
+    });
+    const { model } = await routerRes.json();
+
+    // Fire a minimal completion — 1 output token to keep cost/latency negligible
+    const client = new Together({ apiKey });
+    await client.chat.completions.create({
+      model,
+      messages: [{ role: "user", content: "hi" }],
+      max_tokens: 1,
+    });
+
+    return NextResponse.json({ valid: true });
+  } catch (error: unknown) {
+    const status =
+      typeof error === "object" && error !== null && "status" in error
+        ? (error as { status: number }).status
+        : undefined;
+
+    if (status === 401 || status === 403) {
+      return NextResponse.json({ valid: false, error: "Invalid API key" });
+    }
+
+    return NextResponse.json(
+      { valid: false, error: "Validation failed" },
+      { status: 500 },
+    );
+  }
+}