Refactor USB drive event handlers to core module

Moves the event handling logic for the USB drive selection controls from the main UI script to the `FFUUI.Core.Handlers` module.

This change improves code organization by centralizing UI logic. The handlers were also improved to correctly manage the "Select All" checkbox state.

FFUDevelopment/BuildFFUVM_UI.ps1

@@ -194,31 +194,6 @@ $window.Add_Loaded({
         $script:uiState.Controls.chkLatestCU.IsEnabled = -not $script:uiState.Controls.chkPreviewCU.IsChecked
 
         # USB Drive Detection/Selection logic (Keep existing logic)
-        $script:uiState.Controls.chkSelectAllUSBDrives.Add_Checked({
-                foreach ($item in $script:uiState.Controls.lstUSBDrives.Items) { $item.IsSelected = $true }
-                $script:uiState.Controls.lstUSBDrives.Items.Refresh()
-            })
-        $script:uiState.Controls.chkSelectAllUSBDrives.Add_Unchecked({
-                foreach ($item in $script:uiState.Controls.lstUSBDrives.Items) { $item.IsSelected = $false }
-                $script:uiState.Controls.lstUSBDrives.Items.Refresh()
-            })
-        $script:uiState.Controls.lstUSBDrives.Add_KeyDown({
-                param($eventSource, $keyEvent)
-                if ($keyEvent.Key -eq 'Space') {
-                    $selectedItem = $script:uiState.Controls.lstUSBDrives.SelectedItem
-                    if ($selectedItem) {
-                        $selectedItem.IsSelected = !$selectedItem.IsSelected
-                        $script:uiState.Controls.lstUSBDrives.Items.Refresh()
-                        $allSelected = -not ($script:uiState.Controls.lstUSBDrives.Items | Where-Object { -not $_.IsSelected })
-                        $script:uiState.Controls.chkSelectAllUSBDrives.IsChecked = $allSelected
-                    }
-                }
-            })
-        $script:uiState.Controls.lstUSBDrives.Add_SelectionChanged({
-                param($eventSource, $selChangeEvent)
-                $allSelected = -not ($script:uiState.Controls.lstUSBDrives.Items | Where-Object { -not $_.IsSelected })
-                $script:uiState.Controls.chkSelectAllUSBDrives.IsChecked = $allSelected
-            })
         $script:uiState.Controls.usbSection.Visibility = if ($script:uiState.Controls.chkBuildUSBDriveEnable.IsChecked) { 'Visible' } else { 'Collapsed' }
         $script:uiState.Controls.usbSelectionPanel.Visibility = if ($script:uiState.Controls.chkSelectSpecificUSBDrives.IsChecked) { 'Visible' } else { 'Collapsed' }
         $script:uiState.Controls.chkBuildUSBDriveEnable.Add_Checked({

FFUDevelopment/FFUUI.Core/FFUUI.Core.Handlers.psm1

@@ -3,6 +3,7 @@ function Register-EventHandlers {
     WriteLog "Registering UI event handlers..."
 
     # Build Tab Event Handlers
+    # Build USB Drive Settings Event Handlers
     $State.Controls.btnCheckUSBDrives.Add_Click({
             param($eventSource, $routedEventArgs)
             $window = [System.Windows.Window]::GetWindow($eventSource)
@@ -17,6 +18,49 @@ function Register-EventHandlers {
                 $localState.Controls.lstUSBDrives.SelectedIndex = 0
             }
         })
+        
+    $State.Controls.chkSelectAllUSBDrives.Add_Checked({
+            param($eventSource, $routedEventArgs)
+            $window = [System.Windows.Window]::GetWindow($eventSource)
+            $localState = $window.Tag
+            foreach ($item in $localState.Controls.lstUSBDrives.Items) { $item.IsSelected = $true }
+            $localState.Controls.lstUSBDrives.Items.Refresh()
+        })
+    $State.Controls.chkSelectAllUSBDrives.Add_Unchecked({
+            param($eventSource, $routedEventArgs)
+            # This event also fires for indeterminate state, so only act if it's explicitly false.
+            if ($eventSource.IsChecked -eq $false) {
+                $window = [System.Windows.Window]::GetWindow($eventSource)
+                $localState = $window.Tag
+                foreach ($item in $localState.Controls.lstUSBDrives.Items) { $item.IsSelected = $false }
+                $localState.Controls.lstUSBDrives.Items.Refresh()
+            }
+        })
+    $State.Controls.lstUSBDrives.Add_KeyDown({
+            param($eventSource, $keyEvent)
+            if ($keyEvent.Key -eq 'Space') {
+                $window = [System.Windows.Window]::GetWindow($eventSource)
+                $localState = $window.Tag
+                $selectedItem = $localState.Controls.lstUSBDrives.SelectedItem
+                if ($selectedItem) {
+                    $selectedItem.IsSelected = -not $selectedItem.IsSelected
+                    $localState.Controls.lstUSBDrives.Items.Refresh()
+                    # After toggling, update the 'Select All' checkbox state
+                    $items = $localState.Controls.lstUSBDrives.Items
+                    $allSelected = $items.Count -gt 0 -and ($items | Where-Object { -not $_.IsSelected }).Count -eq 0
+                    $localState.Controls.chkSelectAllUSBDrives.IsChecked = $allSelected
+                }
+            }
+        })
+    $State.Controls.lstUSBDrives.Add_SelectionChanged({
+            param($eventSource, $selChangeEvent)
+            $window = [System.Windows.Window]::GetWindow($eventSource)
+            $localState = $window.Tag
+            $items = $localState.Controls.lstUSBDrives.Items
+            # Update the 'Select All' checkbox state based on current selections
+            $allSelected = $items.Count -gt 0 -and ($items | Where-Object { -not $_.IsSelected }).Count -eq 0
+            $localState.Controls.chkSelectAllUSBDrives.IsChecked = $allSelected
+        })
 
     # Hyper-V tab event handlers
     $State.Controls.cmbVMSwitchName.Add_SelectionChanged({