feat: Implement user search functionality with ViewModel and results display

app/src/main/java/com/rosetta/messenger/MainActivity.kt

@@ -212,12 +212,14 @@ fun MainScreen(
         "+${it.take(1)} ${it.substring(1, 4)} ${it.substring(4, 7)}${it.substring(7)}" 
     } ?: "+7 775 9932587"
     val accountPublicKey = account?.publicKey ?: "04c266b98ae5"
+    val privateKeyHash = account?.privateKeyHash ?: ""
     
     ChatsListScreen(
         isDarkTheme = isDarkTheme,
         accountName = accountName,
         accountPhone = accountPhone,
         accountPublicKey = accountPublicKey,
+        privateKeyHash = privateKeyHash,
         onToggleTheme = onToggleTheme,
         onProfileClick = {
             // TODO: Navigate to profile
@@ -246,6 +248,10 @@ fun MainScreen(
         onNewChat = {
             // TODO: Show new chat screen
         },
+        onUserSelect = { user ->
+            // TODO: Navigate to chat with selected user
+            android.util.Log.d("MainScreen", "User selected: ${user.publicKey}")
+        },
         onLogout = onLogout
     )
 }