feat: add local auth billing and usage management

app/api/usage/route.ts

@@ -0,0 +1,22 @@
+import { jsonError, jsonOk } from "@/lib/server/api";
+import { requireAppUser } from "@/lib/server/auth/current-user";
+import { getPersonalUsageReport } from "@/lib/server/usage-service";
+import type { UsagePreset } from "@/lib/usage";
+
+export const runtime = "nodejs";
+export const dynamic = "force-dynamic";
+
+export async function GET(request: Request) {
+  try {
+    const user = await requireAppUser();
+    const preset = parsePreset(new URL(request.url).searchParams.get("preset"));
+    return jsonOk(await getPersonalUsageReport(user.id, preset));
+  } catch (error) {
+    return jsonError(error, 500, { request, source: "api.usage" });
+  }
+}
+
+function parsePreset(value: string | null): UsagePreset {
+  if (value === "today" || value === "7d" || value === "30d" || value === "month") return value;
+  return "month";
+}