fix: tell offline from a lost connection on screen

With --offline and no list, the full screen said No connection and
offered a Try again that could never work. It now names offline mode
and the two ways a run gets its list without the network. With a list,
the plan counted downloads the run forbids: it says what this machine
can supply and what needs the internet, and the printed command keeps
--offline.

install.ps1

@@ -11,7 +11,7 @@
 
     $ErrorActionPreference = "Stop"
     $defaultInstallUrl = "https://raw.githubusercontent.com/Abdess/retrobios/main/install.py"
-    $defaultInstallSha256 = "eaa912af47dc6f29e4436ec200a1b431b8ddd8006ca08e57c8c73d3a05717818"
+    $defaultInstallSha256 = "1f6b90760303d04cb6beef7fd294371b2e1d4ba733578c59a95e1b0395c2f376"
     $maximumInstallerBytes = 2MB
     $installerExit = 0
     $installer = if ($PSScriptRoot) { Join-Path $PSScriptRoot "install.py" } else { $null }