Add visual parity screenshot diff tool and mock appSettings in dev server

Add pixelmatch-based screenshot comparison script that captures Angular
(:4200) and React (:8080) at every route and generates pixel diff images.

Dev server: add mock /api/appSettings endpoint so Angular can bootstrap
when WAF blocks the real API.

scripts/dev-server.mjs

@@ -40,6 +40,24 @@ await new Promise((r) => setTimeout(r, 18000));
 
 const app = express();
 
+// --- Mock fallback for /api/appSettings when WAF blocks requests ---
+app.get("/api/appSettings", (req, res) => {
+  res.json({
+    showDebugVersion: "False",
+    uiOptions: {
+      isTestVersion: "",
+      filter: {
+        schedule: { searchFrom: "30d", searchTo: "30d", timeStep: "" },
+        onlineboard: { searchFrom: "2d", searchTo: "14d", timeStep: "" },
+      },
+      buttons: {
+        buyTicket: { period: { min: "2h", max: "72h" } },
+        flightStatus: { availableFrom: "24h", visible: "" },
+      },
+    },
+  });
+});
+
 // --- API proxy via curl (bypasses WAF TLS fingerprinting) ---
 app.use(["/api", "/flights"], (req, res) => {
   const targetUrl = `${API_TARGET}${req.originalUrl}`;