Refactor code and improve internationalization support

- Updated import statements to remove invisible characters.
- Standardized comments to use a consistent hyphen format.
- Adjusted username validation error messages for consistency.
- Enhanced email sending functions to include language support.
- Added email internationalization configuration for dynamic translations.
- Updated calendar and federation routes to include language in user queries.
- Improved user feedback messages in German and English for clarity.

src/pages/Calendar.jsx

@@ -1,4 +1,4 @@
-import { useState, useEffect, useMemo } from 'react';
+import { useState, useEffect, useMemo } from 'react';
 import {
   ChevronLeft, ChevronRight, Plus, Calendar as CalendarIcon, Clock, Video,
   Loader2, Download, Share2, Globe, Trash2, Edit, X, UserPlus, Send, ExternalLink,
@@ -494,7 +494,7 @@ export default function Calendar() {
                         style={{ backgroundColor: ev.color || '#6366f1' }}
                       >
                         <div className="truncate">{ev.title}</div>
-                        <div className="opacity-80 text-[10px]">{formatTime(ev.start_time)} – {formatTime(ev.end_time)}</div>
+                        <div className="opacity-80 text-[10px]">{formatTime(ev.start_time)} - {formatTime(ev.end_time)}</div>
                       </div>
                     ))}
                   </div>
@@ -604,7 +604,7 @@ export default function Calendar() {
             <div className="flex items-center gap-2 text-sm text-th-text-s">
               <Clock size={14} />
               <span>
-                {new Date(showDetail.start_time).toLocaleString()} – {new Date(showDetail.end_time).toLocaleString()}
+                {new Date(showDetail.start_time).toLocaleString()} - {new Date(showDetail.end_time).toLocaleString()}
               </span>
             </div>