Make install script idempotent: treat already-up-to-date as success

winget exit code -1978335189 (no applicable update) is now handled
as a non-error for both Firefox and other packages. Summary shows
"Deja a jour" in green instead of failing.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

powershell/libres-softwares-install.ps1

@@ -6,6 +6,9 @@ param()
 
 $ErrorActionPreference = "Continue"
 
+# winget exit code: package already installed and already at latest version
+$WingetExitNoUpdateAvailable = -1978335189
+
 function Initialize-Winget {
     if (Get-Command winget -ErrorAction SilentlyContinue) {
         return
@@ -101,11 +104,16 @@ function Install-FirefoxEsr {
 
         $Process = Start-Process -FilePath "winget" -ArgumentList $Arguments -NoNewWindow -Wait -PassThru
 
+        if ($Process.ExitCode -eq $WingetExitNoUpdateAvailable) {
+            Write-Host "Firefox ESR is already up to date." -ForegroundColor Green
+            return
+        }
+
         if ($Process.ExitCode -ne 0) {
             throw "Firefox ESR installation failed. winget exit code: $($Process.ExitCode)"
         }
 
-        Write-Host "Firefox ESR installed or already present." -ForegroundColor Green
+        Write-Host "Firefox ESR installed or updated." -ForegroundColor Green
     }
 }
 
@@ -435,6 +443,10 @@ foreach ($logiciel in $logicielsAInstaller) {
                 Write-Host "OK $($logiciel.Nom) installe avec succes" -ForegroundColor Green
                 $reussites++
                 $resultats += @{Logiciel = $logiciel.Nom; Statut = "Succes"}
+            } elseif ($process.ExitCode -eq $WingetExitNoUpdateAvailable) {
+                Write-Host "OK $($logiciel.Nom) deja a jour" -ForegroundColor Green
+                $reussites++
+                $resultats += @{Logiciel = $logiciel.Nom; Statut = "Deja a jour"}
             } else {
                 Write-Host "ERREUR Echec de l'installation de $($logiciel.Nom) (Code: $($process.ExitCode))" -ForegroundColor Red
                 $echecs++
@@ -454,7 +466,7 @@ Write-Host "===========================================================" -Foregr
 Write-Host ""
 
 foreach ($resultat in $resultats) {
-    if ($resultat.Statut -eq "Succes") {
+    if ($resultat.Statut -eq "Succes" -or $resultat.Statut -eq "Deja a jour") {
         Write-Host "[OK] $($resultat.Logiciel): $($resultat.Statut)" -ForegroundColor Green
     } else {
         Write-Host "[X] $($resultat.Logiciel): $($resultat.Statut)" -ForegroundColor Red