Copyright: readable pill with proper "© 2026 ASTERION VR — All rights reserved"

The previous copyright was a faded TextBlock at Opacity 0.7 with the
secondary grey color, sitting directly on top of the variable-
luminance background image. Hard to read on the bright spots of the
ASTERION VR engraving.

Wrap it in a Border with #A0000000 background (~63% opacity black)
and CornerRadius=10 — same pill style as the license badge — so the
text reads cleanly regardless of what's behind. Foreground is now
plain white instead of the secondary grey.

Text changed from the terse "© ASTERION VR" to the proper convention:
- UI: "© 2026 ASTERION VR — Tous droits réservés" (matches the
  French-language UI in MainWindow + Settings)
- Assembly metadata (Properties → Détails on the .exe): English form
  "© 2026 ASTERION VR — All rights reserved"

Same change applied to PSLauncher.Updater.csproj.

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

src/PSLauncher.Updater/PSLauncher.Updater.csproj

@@ -11,7 +11,7 @@
     <Version>0.5.0</Version>
     <ApplicationIcon>..\PSLauncher.App\Resources\favicon.ico</ApplicationIcon>
     <Company>ASTERION VR</Company>
-    <Copyright>© ASTERION VR</Copyright>
+    <Copyright>© 2026 ASTERION VR — All rights reserved</Copyright>
 
     <!-- Single-file self-contained pour le publish (~10 Mo) -->
     <PublishSingleFile>true</PublishSingleFile>