refactor: Remove OpenXML dependency and improve Excel COM cleanup

Install-Dependencies.ps1

@@ -39,31 +39,6 @@ foreach ($module in $graphModules) {
     }
 }
 
-# Install OpenXML via NuGet package (not module)
-try {
-    # Install NuGet package provider if not exists
-    if (-not (Get-PackageProvider -Name NuGet)) {
-        Install-PackageProvider -Name NuGet -Force
-    }
-    
-    # Install OpenXML SDK package
-    $openXmlPackage = Install-Package DocumentFormat.OpenXml -ProviderName NuGet -Force -SkipDependencies
-    $packagePath = Join-Path $env:USERPROFILE ".nuget\packages\DocumentFormat.OpenXml"
-    $dllPath = Resolve-Path (Join-Path $packagePath "*\lib\net*\DocumentFormat.OpenXml.dll") -ErrorAction SilentlyContinue | Select-Object -First 1
-
-    if ($dllPath -and (Test-Path $dllPath)) {
-        Add-Type -Path $dllPath
-        Write-Host "DocumentFormat.OpenXml assembly loaded successfully" -ForegroundColor Green
-    }
-    else {
-        throw "OpenXML DLL not found in NuGet packages. Tried path: $packagePath"
-    }
-}
-catch {
-    Write-Host "Failed to install DocumentFormat.OpenXml: $($_.Exception.Message)" -ForegroundColor Red
-    Write-Host "You may need to install the Open XML SDK manually from:"
-    Write-Host "https://www.microsoft.com/en-us/download/details.aspx?id=30425" -ForegroundColor Yellow
-}
 
 # Check for Excel installation
 try {

MainForm.ps1

@@ -2,15 +2,6 @@ Add-Type -AssemblyName System.Windows.Forms
 Import-Module Microsoft.Graph.Sites
 Import-Module Microsoft.Graph.Files
 
-# Load Open XML assembly from installed NuGet package
-try {
-    $openXmlPath = Join-Path $env:USERPROFILE ".nuget\packages\DocumentFormat.OpenXml\*\lib\net46\DocumentFormat.OpenXml.dll"
-    Add-Type -Path (Resolve-Path $openXmlPath -ErrorAction Stop)
-}
-catch {
-    [System.Windows.Forms.MessageBox]::Show("OpenXML assembly missing! Install dependencies first.")
-    exit
-}
 
 # Import our components
 . "$PSScriptRoot\GraphConfig.ps1"