app: port app to use the system package

This commit does away with almost all baggage left over from the Ego port. Error wrapping also got simplified. All API changes happens to be internal which means no changes to main except renaming of the BaseError type.

Signed-off-by: Ophestra Umiker <cat@ophivana.moe>

internal/app/launch.sudo.go

@@ -14,7 +14,7 @@ func (a *app) commandBuilderSudo(shimEnv string) (args []string) {
 	args = make([]string, 0, 8)
 
 	// -Hiu $USER
-	args = append(args, "-Hiu", a.seal.sys.Username)
+	args = append(args, "-Hiu", a.seal.sys.user.Username)
 
 	// -A?
 	if _, ok := os.LookupEnv(sudoAskPass); ok {