fix: clear channel messages on reset (#446)

When `clearMessages` is called, it now also clears the `channelMessages` in the state, ensuring that messages from specific channels are also removed.

Co-authored-by: elian.kumaraku <elian.kumaraku@creactives.com>

app/src/main/java/com/bitchat/android/ui/MessageManager.kt

@@ -37,6 +37,7 @@ class MessageManager(private val state: ChatState) {
     
     fun clearMessages() {
         state.setMessages(emptyList())
+        state.setChannelMessages(emptyMap())
     }
     
     // MARK: - Channel Message Management