feat: count game data apart from BIOS files

The installer knew BIOS files from game data and no count showed it.
The plan, the line menu and the result count them apart for a list that
marks game data, the plan gets a game data row and the menu a g key,
each toggling it in one press, and one sentence says what game data is.

install.ps1

@@ -11,7 +11,7 @@
 
     $ErrorActionPreference = "Stop"
     $defaultInstallUrl = "https://raw.githubusercontent.com/Abdess/retrobios/main/install.py"
-    $defaultInstallSha256 = "c3dcd0682ff917866b79f7718de048e16f13d03651111601e1816ec49f5703cb"
+    $defaultInstallSha256 = "af62c61703cf1becc150b0244b6e13c731e062e9471a07c184693bb9cd46ece3"
     $maximumInstallerBytes = 2MB
     $installerExit = 0
     $installer = if ($PSScriptRoot) { Join-Path $PSScriptRoot "install.py" } else { $null }