feat: add install.ps1 powershell installer

install.ps1

@@ -0,0 +1,104 @@
+# RetroBIOS installer for Windows (PowerShell 5+, no Python required)
+$ErrorActionPreference = "Stop"
+$baseUrl = "https://raw.githubusercontent.com/Abdess/retrobios/main"
+$releaseUrl = "https://github.com/Abdess/retrobios/releases/download/large-files"
+
+$platform = $null
+$biosPath = $null
+
+# Detect EmuDeck
+$emudeckSettings = Join-Path $env:APPDATA "EmuDeck\settings.ps1"
+if (Test-Path $emudeckSettings) {
+    $content = Get-Content $emudeckSettings -Raw
+    if ($content -match '\$emulationPath\s*=\s*"([^"]+)"') {
+        $platform = "emudeck"
+        $biosPath = Join-Path $Matches[1] "bios"
+        Write-Host "Found EmuDeck at $biosPath"
+    }
+}
+
+# Detect RetroArch
+if (-not $platform) {
+    $raCfg = Join-Path $env:APPDATA "RetroArch\retroarch.cfg"
+    if (Test-Path $raCfg) {
+        $platform = "retroarch"
+        $biosPath = Join-Path $env:APPDATA "RetroArch\system"
+        foreach ($line in Get-Content $raCfg) {
+            if ($line -match '^\s*system_directory\s*=\s*"?([^"]+)"?') {
+                $val = $Matches[1].Trim()
+                if ($val -and $val -ne "default") {
+                    $biosPath = $val
+                }
+                break
+            }
+        }
+        Write-Host "Found RetroArch at $biosPath"
+    }
+}
+
+# Fallback
+if (-not $platform) {
+    $platform = Read-Host "Platform (retroarch, batocera, emudeck, ...)"
+    $biosPath = Read-Host "BIOS directory path"
+    if (-not $platform -or -not $biosPath) {
+        Write-Host "Aborted." -ForegroundColor Red; exit 1
+    }
+}
+
+Write-Host "`nFetching file index for $platform..."
+$manifest = Invoke-RestMethod "$baseUrl/install/$platform.json"
+$files = $manifest.files
+Write-Host "  $($files.Count) files"
+
+Write-Host "`nChecking existing files..."
+$toDownload = @()
+$upToDate = 0
+
+foreach ($f in $files) {
+    $dest = Join-Path $biosPath $f.dest
+    if (Test-Path $dest) {
+        if ($f.sha1) {
+            $actual = (Get-FileHash $dest -Algorithm SHA1).Hash.ToLower()
+            if ($actual -eq $f.sha1) { $upToDate++; continue }
+        } else {
+            $upToDate++; continue
+        }
+    }
+    $toDownload += $f
+}
+
+Write-Host "  $upToDate/$($files.Count) up to date, $($toDownload.Count) to download"
+
+if ($toDownload.Count -eq 0) {
+    Write-Host "`nDone. 0 downloaded, $upToDate already up to date."
+    exit 0
+}
+
+$downloaded = 0
+$errors = 0
+$total = $toDownload.Count
+
+foreach ($f in $toDownload) {
+    $dest = Join-Path $biosPath $f.dest
+    $dir = Split-Path $dest -Parent
+    if (-not (Test-Path $dir)) { New-Item -ItemType Directory -Path $dir -Force | Out-Null }
+
+    if ($f.release_asset) {
+        $url = "$releaseUrl/$($f.release_asset)"
+    } else {
+        $url = "$baseUrl/$($f.repo_path)"
+    }
+
+    try {
+        Invoke-WebRequest -Uri $url -OutFile $dest -UseBasicParsing
+        $downloaded++
+        $i = $downloaded + $errors
+        Write-Host "  [$i/$total] $($f.dest) ok"
+    } catch {
+        $errors++
+        $i = $downloaded + $errors
+        Write-Host "  [$i/$total] $($f.dest) FAILED" -ForegroundColor Red
+    }
+}
+
+Write-Host "`nDone. $downloaded downloaded, $upToDate already up to date."