Add public OBS overlay modes, themes and token protection

server.js

@@ -268,6 +268,16 @@ app.post("/api/export/pdf", (req, res) => {
   }
 });
 
+const PUBLIC_OVERLAY_TOKEN = String(process.env.PUBLIC_OVERLAY_TOKEN || "").trim();
+
+app.get(["/public-overlay", "/public-overlay/:mode"], (req, res) => {
+  if (PUBLIC_OVERLAY_TOKEN && String(req.query.token || "").trim() !== PUBLIC_OVERLAY_TOKEN) {
+    res.status(403).type("text/plain").send("Forbidden");
+    return;
+  }
+  res.sendFile(path.join(__dirname, "index.html"));
+});
+
 app.use(
   express.static(__dirname, {
     setHeaders: (res, filePath) => {