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>

installer/PSLauncher.iss

@@ -35,7 +35,7 @@ DefaultGroupName={#MyAppName}
 DisableProgramGroupPage=yes
 OutputDir=output
 OutputBaseFilename=PSLauncher-Setup-{#MyAppVersion}
-SetupIconFile=
+SetupIconFile=..\src\PSLauncher.App\Resources\favicon.ico
 Compression=lzma2/ultra
 SolidCompression=yes
 WizardStyle=modern