fix: unread badge counts messages from new conversation system

The badge endpoint api_unread_count only counted legacy private_messages
and group_messages. Now also counts unread conv_messages from the new
conversations system, fixing phantom unread counts for users.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

blueprints/messages/routes.py

@@ -669,7 +669,23 @@ def api_unread_count():
                 q = q.filter(GroupMessage.created_at > m.last_read_at)
             group_count += q.scalar() or 0
 
-        return jsonify({'count': pm_count + group_count})
+        # Conversations unread (new messaging system)
+        from database import ConversationMember, ConvMessage
+        conv_count = 0
+        conv_memberships = db.query(ConversationMember).filter(
+            ConversationMember.user_id == current_user.id,
+            ConversationMember.is_archived == False
+        ).all()
+        for cm in conv_memberships:
+            q = db.query(func.count(ConvMessage.id)).filter(
+                ConvMessage.conversation_id == cm.conversation_id,
+                ConvMessage.sender_id != current_user.id
+            )
+            if cm.last_read_at:
+                q = q.filter(ConvMessage.created_at > cm.last_read_at)
+            conv_count += q.scalar() or 0
+
+        return jsonify({'count': pm_count + group_count + conv_count})
     finally:
         db.close()