improve subscribe to messages

src/components/SupportChat.vue

@@ -1,5 +1,5 @@
 <script setup lang="ts">
-import { ref, computed, nextTick, onMounted, watch } from 'vue'
+import { ref, computed, nextTick, onMounted, watch, onUnmounted } from 'vue'
 import { useNostrStore } from '@/stores/nostr'
 import { npubToHex } from '@/lib/nostr'
 import type { DirectMessage } from '@/types/nostr'
@@ -79,6 +79,25 @@ onMounted(async () => {
   }
 })
 
+// Add cleanup on unmount
+onUnmounted(() => {
+  if (nostrStore.activeChat) {
+    nostrStore.unsubscribeFromMessages()
+  }
+})
+
+// Watch for changes in activeChat
+watch(() => nostrStore.activeChat, async (newChat) => {
+  if (newChat) {
+    try {
+      await nostrStore.subscribeToMessages()
+    } catch (err) {
+      console.error('Failed to subscribe to messages:', err)
+      error.value = 'Failed to connect to chat. Please try again later.'
+    }
+  }
+})
+
 function scrollToBottom() {
   if (messagesEndRef.value) {
     messagesEndRef.value.scrollIntoView({ behavior: 'smooth' })