Align preview typography with FFmpeg output, add video/song title split, and ship OSS updates.

Separate YouTube video titles from on-video song/artist fields with Pro gating, serve curated fonts and watermark assets for 1:1 preview parity, and include billing/API/docs/deploy stack for self-hosted release.

lib/stripe.ts

@@ -0,0 +1,30 @@
+import Stripe from "stripe";
+
+let stripe: Stripe | null = null;
+
+export function getStripe(): Stripe {
+  const key = process.env.STRIPE_SECRET_KEY;
+  if (!key) {
+    throw new Error("STRIPE_SECRET_KEY is not configured");
+  }
+  if (!stripe) {
+    stripe = new Stripe(key);
+  }
+  return stripe;
+}
+
+export function isStripeConfigured(): boolean {
+  return Boolean(process.env.STRIPE_SECRET_KEY);
+}
+
+/**
+ * Bypass Stripe Checkout when:
+ * - BILLING_DEV_MOCK=true, or
+ * - development and no STRIPE_SECRET_KEY (so UI still works without stripe listen)
+ * Set BILLING_DEV_MOCK=false to force real Stripe even without keys (will 503).
+ */
+export function isBillingDevMock(): boolean {
+  if (process.env.BILLING_DEV_MOCK === "true") return true;
+  if (process.env.BILLING_DEV_MOCK === "false") return false;
+  return process.env.NODE_ENV === "development" && !process.env.STRIPE_SECRET_KEY;
+}