[no ci] add windows install script

eng/install/install.ps1

@@ -0,0 +1,71 @@
+# Install script that downloads Metamod:Source and Counter-Strike Sharp (with runtime)
+
+$MM_DOWNLOAD_URL = "https://mms.alliedmods.net/mmsdrop/2.0/mmsource-2.0.0-git1286-windows.zip"
+$TARGET_DIR = "./game/csgo"
+$GAMEINFO_FILE = Join-Path $TARGET_DIR "gameinfo.gi"
+$ProgressPreference = 'SilentlyContinue'
+
+# Verification
+if (-not (Test-Path $GAMEINFO_FILE)) {
+    Write-Error "Error: $GAMEINFO_FILE does not exist in the specified directory."
+    exit 1
+}
+
+# GitHub API for Counter-Strike Sharp Releases
+$RELEASE_INFO = (Invoke-WebRequest -Uri "https://api.github.com/repos/roflmuffin/CounterStrikeSharp/releases/latest").Content | ConvertFrom-Json
+
+# Filtering download URLs
+$CSSHARP_DOWNLOAD_URL = $RELEASE_INFO.assets | 
+    Where-Object { $_.browser_download_url -like '*windows*.zip*' -and $_.browser_download_url -notlike '*with-runtime*' } | 
+    Select-Object -First 1 -ExpandProperty browser_download_url
+
+$CSSHARP_RUNTIME_DOWNLOAD_URL = $RELEASE_INFO.assets | 
+    Where-Object { $_.browser_download_url -like '*windows*.zip*' -and $_.browser_download_url -like '*with-runtime*' } | 
+    Select-Object -First 1 -ExpandProperty browser_download_url
+
+### METAMOD:SOURCE ###
+Write-Output "Downloading Metamod:Source..."
+
+Invoke-WebRequest -Uri $MM_DOWNLOAD_URL -OutFile metamod.zip
+Write-Output "Extracting Metamod:Source to $TARGET_DIR..."
+Expand-Archive -Force -Path metamod.zip -DestinationPath $TARGET_DIR
+Remove-Item metamod.zip 
+
+### GAMEINFO.GI UPDATE ###
+$NEW_ENTRY = "			Game    csgo/addons/metamod"
+$FILE_CONTENT = Get-Content $GAMEINFO_FILE
+
+Write-Output "Updating $GAMEINFO_FILE..."
+if ($FILE_CONTENT -contains $NEW_ENTRY) {
+    Write-Output "The entry '$NEW_ENTRY' already exists in $GAMEINFO_FILE. No changes were made."
+} else {
+    $Pattern = "Game_LowViolence"
+    $Modified = $false
+    $NewContent = @()
+
+    foreach ($line in $FILE_CONTENT) {
+        if ($line -match $Pattern -and -not $Modified) {
+            $NewContent += $line
+            $NewContent += $NEW_ENTRY
+            $Modified = $true
+        } else {
+            $NewContent += $line
+        }
+    }
+
+    $NewContent | Set-Content $GAMEINFO_FILE
+    Write-Host "The file $GAMEINFO_FILE has been modified successfully. '$NEW_ENTRY' has been added."
+}
+
+### COUNTER-STRIKE SHARP ###
+Write-Output "Downloading Counter-Strike Sharp (with runtime)..."
+
+# Determine if runtime needs to be downloaded
+if (-not (Test-Path "./game/csgo/addons/CounterStrikeSharp/dotnet/dotnet.exe")) {
+    $CSSHARP_DOWNLOAD_URL = $CSSHARP_RUNTIME_DOWNLOAD_URL
+}
+
+Invoke-WebRequest -Uri $CSSHARP_DOWNLOAD_URL -OutFile cssharp.zip
+Write-Output "Extracting Counter-Strike Sharp to $TARGET_DIR..."
+Expand-Archive -Force -Path cssharp.zip -DestinationPath $TARGET_DIR
+Remove-Item cssharp.zip