feat: Implement sorting of peers by latest message timestamp and unread status in Nostr chat

- Introduce a computed property to sort peers based on the latest message timestamp and unread message count, enhancing the user experience by prioritizing relevant conversations.
- Add methods to track and retrieve the latest message timestamp for each peer, ensuring accurate sorting.
- Update the ChatComponent to utilize the new sorting logic, improving the display of peers in the chat interface.

refactor: Reorganize fuzzy search and mobile detection logic in ChatComponent

- Move fuzzy search implementation and mobile detection methods to improve code clarity and maintainability.
- Ensure consistent functionality for searching peers by username or pubkey with typo tolerance.
- Maintain mobile navigation logic for better user experience on smaller devices.

src/composables/useNostrChat.ts

@@ -74,6 +74,9 @@ export function useNostrChat() {
   
   // Reactive unread counts
   const unreadCounts = ref<Map<string, number>>(new Map())
+  
+  // Track latest message timestamp for each peer (for sorting)
+  const latestMessageTimestamps = ref<Map<string, number>>(new Map())
 
   // Computed
   const isLoggedIn = computed(() => !!currentUser.value)
@@ -97,6 +100,26 @@ export function useNostrChat() {
     return total
   }
 
+  // Get latest message timestamp for a peer
+  const getLatestMessageTimestamp = (peerPubkey: string): number => {
+    return latestMessageTimestamps.value.get(peerPubkey) || 0
+  }
+
+  // Get all latest message timestamps
+  const getAllLatestMessageTimestamps = (): Map<string, number> => {
+    return new Map(latestMessageTimestamps.value)
+  }
+
+  // Update latest message timestamp for a peer
+  const updateLatestMessageTimestamp = (peerPubkey: string, timestamp: number): void => {
+    const currentLatest = latestMessageTimestamps.value.get(peerPubkey) || 0
+    if (timestamp > currentLatest) {
+      latestMessageTimestamps.value.set(peerPubkey, timestamp)
+      // Force reactivity
+      latestMessageTimestamps.value = new Map(latestMessageTimestamps.value)
+    }
+  }
+
   // Update unread count for a peer
   const updateUnreadCount = (peerPubkey: string, count: number): void => {
     if (count > 0) {
@@ -584,6 +607,9 @@ export function useNostrChat() {
       // Force reactivity by triggering a change
       messages.value = new Map(messages.value)
       
+      // Update latest message timestamp for this peer (for sorting)
+      updateLatestMessageTimestamp(peerPubkey, message.created_at)
+      
       // Track unread messages (only for received messages, not sent ones)
       if (!isSentByMe) {
         const unreadData = getUnreadData(peerPubkey)
@@ -748,6 +774,9 @@ export function useNostrChat() {
       // Force reactivity by triggering a change
       messages.value = new Map(messages.value)
       
+      // Update latest message timestamp for this peer (for sorting)
+      updateLatestMessageTimestamp(peerPubkey, message.created_at)
+      
       // Trigger callback if set
       if (onMessageAdded.value) {
         onMessageAdded.value(peerPubkey)
@@ -792,6 +821,10 @@ export function useNostrChat() {
     getTotalUnreadCount,
     clearAllUnreadCounts,
     clearProcessedMessageIds,
-    debugUnreadData
+    debugUnreadData,
+    
+    // Timestamp methods (for sorting)
+    getLatestMessageTimestamp,
+    getAllLatestMessageTimestamps
   }
 }