Initial scaffolding: PS_Launcher v0.2

Client (C# / .NET 8 / WPF, MVVM via CommunityToolkit.Mvvm):
- PSLauncher.App: WPF UI dark theme (Epic-style sidebar + hero + big play button)
  with UpdateAvailableDialog rendering Markdown release notes via Markdig.Wpf.
- PSLauncher.Core: services for installation registry (scans Proserve v{X.Y.Z}/),
  process launcher, manifest fetch, SHA-256 integrity, HTTP download with
  progress, ZIP install via .tmp + atomic rename, update orchestrator.
- PSLauncher.Models: RemoteManifest, InstalledVersion, LocalConfig DTOs.

Server (PHP 8 for OVH mutualisé, deployed under www/PS_Launcher/):
- Front controller + routes /manifest and /releasenotes/{version}.
- Static signed-manifest workflow with tools/sign-manifest.php CLI to
  recompute SHA-256 and sizeBytes after each ZIP upload.
- .htaccess: HTTPS redirect, rewrite, security headers.
- config.example.php template; real config.php is gitignored.

Cohabiting versions: each release lives in its own Proserve v{version}/ folder
under installRoot. Old versions are never deleted automatically.

Roadmap: v0.3 = HTTP Range resume + Polly retry + state.json,
v0.4 = MySQL license + Ed25519 signatures + DPAPI, v0.5 = settings/UX polish.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/PSLauncher.Core/Updates/IUpdateChecker.cs

@@ -0,0 +1,16 @@
+using PSLauncher.Models;
+
+namespace PSLauncher.Core.Updates;
+
+public interface IUpdateChecker
+{
+    Task<UpdateCheckResult> CheckAsync(CancellationToken ct);
+}
+
+public sealed record UpdateCheckResult(
+    RemoteManifest? Manifest,
+    VersionManifest? LatestRemote,
+    InstalledVersion? CurrentInstalled,
+    bool IsLatestInstalled,
+    bool IsLatestNewerThanInstalled,
+    string? Error);

src/PSLauncher.Core/Updates/UpdateChecker.cs

@@ -0,0 +1,53 @@
+using Microsoft.Extensions.Logging;
+using PSLauncher.Core.Installations;
+using PSLauncher.Core.Manifests;
+using PSLauncher.Models;
+
+namespace PSLauncher.Core.Updates;
+
+public sealed class UpdateChecker : IUpdateChecker
+{
+    private readonly IManifestService _manifestService;
+    private readonly IInstallationRegistry _registry;
+    private readonly ILogger<UpdateChecker> _logger;
+
+    public UpdateChecker(
+        IManifestService manifestService,
+        IInstallationRegistry registry,
+        ILogger<UpdateChecker> logger)
+    {
+        _manifestService = manifestService;
+        _registry = registry;
+        _logger = logger;
+    }
+
+    public async Task<UpdateCheckResult> CheckAsync(CancellationToken ct)
+    {
+        try
+        {
+            var manifest = await _manifestService.FetchAsync(ct).ConfigureAwait(false);
+            var latest = manifest.Versions.FirstOrDefault(v => v.Version == manifest.Latest)
+                         ?? manifest.Versions
+                             .OrderByDescending(v => SemVer.Parse(v.Version))
+                             .FirstOrDefault();
+
+            var installed = _registry.Scan();
+            var latestInstalled = installed
+                .OrderByDescending(v => SemVer.Parse(v.Version))
+                .FirstOrDefault();
+
+            var isLatestInstalled = latest is not null && latestInstalled is not null
+                                    && latestInstalled.Version == latest.Version;
+            var isNewer = latest is not null
+                          && (latestInstalled is null
+                              || SemVer.Parse(latest.Version).CompareTo(SemVer.Parse(latestInstalled.Version)) > 0);
+
+            return new UpdateCheckResult(manifest, latest, latestInstalled, isLatestInstalled, isNewer, null);
+        }
+        catch (Exception ex)
+        {
+            _logger.LogError(ex, "Update check failed");
+            return new UpdateCheckResult(null, null, null, false, false, ex.Message);
+        }
+    }
+}