feat(telegram): improve group handling and default display name to @username

- /lottosettings now opens settings in private DM instead of group
- Bot only reacts to / commands in groups (keyboard buttons ignored)
- Reply keyboard buttons removed from group messages
- Default display name now uses @username instead of 'Anon'
- Users can still manually update display name in settings
- Updated all display name usages to use centralized getDisplayName()

telegram_bot/src/services/database.ts

@@ -165,6 +165,7 @@ class BotDatabase {
 
   /**
    * Create a new user
+   * Default display name is @username if available, otherwise 'Anon'
    */
   createUser(
     telegramId: number,
@@ -175,13 +176,15 @@ class BotDatabase {
     if (!this.db) throw new Error('Database not initialized');
 
     const now = new Date().toISOString();
+    // Default display name: @username if available, otherwise 'Anon'
+    const defaultDisplayName = username ? `@${username}` : 'Anon';
     
     this.db.prepare(`
       INSERT INTO users (telegram_id, username, first_name, last_name, display_name, created_at, updated_at)
-      VALUES (?, ?, ?, ?, 'Anon', ?, ?)
-    `).run(telegramId, username || null, firstName || null, lastName || null, now, now);
+      VALUES (?, ?, ?, ?, ?, ?, ?)
+    `).run(telegramId, username || null, firstName || null, lastName || null, defaultDisplayName, now, now);
 
-    logger.info('New user created', { telegramId, username });
+    logger.info('New user created', { telegramId, username, displayName: defaultDisplayName });
     
     return this.getUser(telegramId)!;
   }

telegram_bot/src/services/notificationScheduler.ts

@@ -173,7 +173,7 @@ class NotificationScheduler {
           if (status.result.is_winner) {
             const user = await stateManager.getUser(telegramId);
             winnerTelegramId = telegramId;
-            winnerDisplayName = user?.displayName || 'Anon';
+            winnerDisplayName = user ? stateManager.getDisplayName(user) : 'Anon';
             
             const winningTicket = status.tickets.find(t => t.is_winning_ticket);
             if (winningTicket) {
@@ -396,7 +396,7 @@ class NotificationScheduler {
           if (status.result.is_winner) {
             const user = await stateManager.getUser(telegramId);
             winnerTelegramId = telegramId;
-            winnerDisplayName = user?.displayName || 'Anon';
+            winnerDisplayName = user ? stateManager.getDisplayName(user) : 'Anon';
             
             const winningTicket = status.tickets.find(t => t.is_winning_ticket);
             if (winningTicket) {

telegram_bot/src/services/state.ts

@@ -170,9 +170,17 @@ class StateManager {
 
   /**
    * Get user's display name (for announcements)
+   * Priority: displayName > @username > 'Anon'
    */
   getDisplayName(user: TelegramUser): string {
-    return user.displayName || 'Anon';
+    if (user.displayName && user.displayName !== 'Anon') {
+      return user.displayName;
+    }
+    // Fall back to @username if available
+    if (user.username) {
+      return `@${user.username}`;
+    }
+    return 'Anon';
   }
 
   /**