UI improvements and rename rooms to channels

- Changed system messages from green to grey with consistent 12pt font
- Fixed text wrapping to flow naturally under timestamps
- Changed default nickname to anonXXXX format
- Replaced text with icon representations in status bar
- Added icons to sidebar section headers
- Made autocomplete UI consistent between commands and @mentions
- Added welcome message for new users (3 second delay)
- Changed sidebar header to 'YOUR NETWORK'
- Added command aliases (/join, /msg)
- Implemented /hug and /slap commands with haptic feedback
- Improved command help display with alphabetization
- Renamed 'rooms' to 'channels' throughout entire codebase

bitchat/Services/NotificationService.swift

@@ -61,7 +61,7 @@ class NotificationService {
     }
     
     func sendMentionNotification(from sender: String, message: String) {
-        let title = "Mentioned by \(sender)"
+        let title = "＠🫵 you were mentioned by \(sender)"
         let body = message
         let identifier = "mention-\(UUID().uuidString)"
         
@@ -69,7 +69,7 @@ class NotificationService {
     }
     
     func sendPrivateMessageNotification(from sender: String, message: String) {
-        let title = "Private message from \(sender)"
+        let title = "🔒 private message from \(sender)"
         let body = message
         let identifier = "private-\(UUID().uuidString)"
         
@@ -83,4 +83,4 @@ class NotificationService {
         
         sendLocalNotification(title: title, body: body, identifier: identifier)
     }
-}
+}