chore: update project references and add Citron copyright

- Replaced all references to the old project name with Citron.
- Added Citron copyright information alongside existing notices in all files.

src/network/verify_user.h

@@ -12,7 +12,7 @@ struct UserData {
     std::string username;
     std::string display_name;
     std::string avatar_url;
-    bool moderator = false; ///< Whether the user is a yuzu Moderator.
+    bool moderator = false; ///< Whether the user is a citron Moderator.
 };
 
 /**