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/edition.ts

@@ -0,0 +1,9 @@
+import { Plan } from "@prisma/client";
+
+export function isSelfHostedEdition(): boolean {
+  return process.env.S2VID_EDITION === "selfhosted";
+}
+
+export function hasProFeatures(plan: Plan): boolean {
+  return isSelfHostedEdition() || plan === "PREMIUM";
+}