Allow custom BYO app list file paths in UI

Updates the FFU UI and orchestration scripts to allow users to specify custom file paths for their Bring Your Own (BYO) app lists, rather than forcing the use of `UserAppList.json` in a specific directory.

Also modifies the orchestration to sync this custom path via `AppInstallConfig.json` so that the runtime orchestration phase resolves the correct file name and path during installation. Refreshes the Apps ISO if the custom BYO app list is updated.

FFUDevelopment/FFU.Common/FFU.Common.Winget.psm1

@@ -358,6 +358,8 @@ function Start-WingetAppDownloadTask {
         [string]$AppListJsonPath,
         [Parameter(Mandatory = $true)]
         [string]$AppsPath,
+        [Parameter()]
+        [string]$UserAppListPath,
         [Parameter(Mandatory = $true)]
         [string]$OrchestrationPath,
         [Parameter(Mandatory = $true)]
@@ -379,11 +381,11 @@ function Start-WingetAppDownloadTask {
     WriteLog "Starting download task for $($appName) with ID $($appId) from source $($source)."
 
     try {
-        # Define paths
-        $userAppListPath = Join-Path -Path $AppsPath -ChildPath "UserAppList.json"
+        # Resolve the BYO app list path so duplicate checks honor custom file names.
+        $userAppListPath = if (-not [string]::IsNullOrWhiteSpace($UserAppListPath)) { $UserAppListPath } else { Join-Path -Path $AppsPath -ChildPath "UserAppList.json" }
         $appFound = $false
 
-        # 1. Check UserAppList.json and content
+        # 1. Check the configured BYO app list and content
         if (Test-Path -Path $userAppListPath) {
             try {
                 $userAppListContent = Get-Content -Path $userAppListPath -Raw | ConvertFrom-Json
@@ -724,6 +726,8 @@ function Get-Apps {
         [string]$AppList,
         [Parameter(Mandatory = $true)]
         [string]$AppsPath,
+        [Parameter()]
+        [string]$UserAppListPath,
         [Parameter(Mandatory = $true)]
         [string]$WindowsArch,
         [Parameter(Mandatory = $true)]
@@ -787,6 +791,7 @@ function Get-Apps {
     # CLI builds should create WinGetWin32Apps.json, so SkipWin32Json is false
     $taskArguments = @{
         AppsPath          = $AppsPath
+        UserAppListPath   = $UserAppListPath
         AppListJsonPath   = $AppList
         OrchestrationPath = $OrchestrationPath
         WindowsArch       = $WindowsArch