fix: address code review findings from 2026-08-17

- scope no-cache headers to non-static routes (restore immutable asset caching)
- reset cached rejected MongoDB promise so retries can succeed
- use last X-Forwarded-For entry in Content Editor rate limiter (anti-spoofing)
- remove weak Mongo defaults from compose files (fail loudly on missing env)
- move staging banner text to common.json content
- read APP_PORT from env file in deploy.sh healthcheck
- filter network noise from staging smoke console assertions

Closes MITHOME-48, MITHOME-49, MITHOME-50, MITHOME-51, MITHOME-52, MITHOME-53, MITHOME-54

proto/src/app/layout.tsx

@@ -6,6 +6,7 @@ import Header from "../components/Header";
 import Footer from "../components/Footer";
 import { ThemeProvider } from "../components/ThemeProvider";
 import { siteConfig } from "../config/site";
+import { common } from "../content";
 
 const geistSans = Geist({
   variable: "--font-geist-sans",
@@ -93,7 +94,7 @@ export default function RootLayout({
         <ThemeProvider>
           {isStaging && (
             <div className="bg-amber-400 px-4 py-2 text-center text-xs font-extrabold tracking-[0.18em] text-amber-950 sm:text-sm">
-              ⚠ STAGING / TESZTKÖRNYEZET — A STAGING OLDALT LÁTOD
+              {common.staging.banner}
             </div>
           )}
           <Header />