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.App/Views/SettingsDialog.xaml

@@ -3,6 +3,7 @@
         xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
         xmlns:vm="clr-namespace:PSLauncher.App.ViewModels"
         Title="Paramètres"
+        Icon="pack://application:,,,/Resources/favicon.ico"
         Width="640" Height="720"
         MinWidth="540" MinHeight="500"
         WindowStartupLocation="CenterOwner"
@@ -234,6 +235,10 @@
                             <Run Text="Version : " />
                             <Run Text="{Binding LauncherVersion, Mode=OneWay}" FontWeight="SemiBold" />
                         </TextBlock>
+                        <TextBlock Text="© ASTERION VR — Tous droits réservés"
+                                   FontSize="12"
+                                   Foreground="{StaticResource Brush.Text.Secondary}"
+                                   Margin="0,4,0,0" />
                         <Grid Margin="0,8,0,0">
                             <Grid.ColumnDefinitions>
                                 <ColumnDefinition Width="*" />