heavily simplify server and app content. unify styling

app/composables/useWebRTCFailureReason.js

@@ -1,18 +1,13 @@
-/**
- * Fetch WebRTC failure reason (e.g. wrong host). Pure: same inputs → same output.
- * @returns {Promise<{ wrongHost: { serverHostname: string, clientHostname: string } | null }>} Failure reason or null.
- */
+/** Pure: fetches WebRTC failure reason (e.g. wrong host). Returns frozen object. */
 export async function getWebRTCFailureReason() {
   try {
     const res = await $fetch('/api/live/debug-request-host', { credentials: 'include' })
     const clientHostname = typeof window !== 'undefined' ? window.location.hostname : ''
     const serverHostname = res?.hostname ?? ''
     if (serverHostname && clientHostname && serverHostname !== clientHostname) {
-      return { wrongHost: { serverHostname, clientHostname } }
+      return Object.freeze({ wrongHost: Object.freeze({ serverHostname, clientHostname }) })
     }
   }
-  catch {
-    // ignore
-  }
-  return { wrongHost: null }
+  catch { /* ignore */ }
+  return Object.freeze({ wrongHost: null })
 }