feat(logging): implement centralized logging system and replace console errors with structured logs

feat(federation): add room sync and deletion notification endpoints for federated instances

fix(federation): handle room deletion and update settings during sync process

feat(federation): enhance FederatedRoomCard and FederatedRoomDetail components to display deleted rooms

i18n: add translations for room deletion messages in English and German

server/config/mailer.js

@@ -1,4 +1,5 @@
 import nodemailer from 'nodemailer';
+import { log } from './logger.js';
 
 let transporter;
 
@@ -20,7 +21,7 @@ export function initMailer() {
   const pass = process.env.SMTP_PASS;
 
   if (!host || !user || !pass) {
-    console.warn('⚠️  SMTP not configured – email verification disabled');
+    log.mailer.warn('SMTP not configured – email verification disabled');
     return false;
   }
 
@@ -34,7 +35,7 @@ export function initMailer() {
     socketTimeout: 15_000,     // 15 s of inactivity before abort
   });
 
-  console.log('✅ SMTP mailer configured');
+  log.mailer.info('SMTP mailer configured');
   return true;
 }