branding: ASTERION VR favicon + copyright everywhere

Icon
----
src/favicon64.jpg converted to favicon.ico (single-resolution 64x64)
via PowerShell + System.Drawing.Icon.FromHandle. The .ico is now an
EmbeddedResource of PSLauncher.App and referenced as:
- <ApplicationIcon> on PSLauncher.App.csproj → .exe icon in
  Explorer / taskbar / Alt-Tab
- Window.Icon on every WPF window: MainWindow, SettingsDialog,
  OnboardingDialog, LicenseDetailsDialog, UpdateAvailableDialog,
  ReleaseNotesViewerDialog, LauncherUpdateDialog
- <ApplicationIcon> on PSLauncher.Updater.csproj → updater also
  carries the brand icon
- SetupIconFile in installer/PSLauncher.iss → the Inno Setup .exe
  installer shows the icon too

Copyright
---------
- <Company>, <Product>, <Copyright> assembly attributes set in
  both csprojs → properties dialog on the .exe shows "© ASTERION VR".
- MainWindow body has a discreet floating "© ASTERION VR" text in the
  bottom-right, mirroring the "Vérifier les MAJ" button on the left.
  Opacity 0.7 + secondary color so it doesn't compete with the cards.
- SettingsDialog "Logs & Application" section gains a
  "© ASTERION VR — Tous droits réservés" line under the version.

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

src/PSLauncher.Updater/PSLauncher.Updater.csproj

@@ -9,6 +9,9 @@
     <AssemblyName>PSLauncher.Updater</AssemblyName>
     <RootNamespace>PSLauncher.Updater</RootNamespace>
     <Version>0.5.0</Version>
+    <ApplicationIcon>..\PSLauncher.App\Resources\favicon.ico</ApplicationIcon>
+    <Company>ASTERION VR</Company>
+    <Copyright>© ASTERION VR</Copyright>
 
     <!-- Single-file self-contained pour le publish (~10 Mo) -->
     <PublishSingleFile>true</PublishSingleFile>