l10n: make German and Brazilian Portuguese selectable

The Weblate merge (#8) landed values-de and values-pt-rBR, but
locales_config.xml still listed only `en`. That file is the single source
of truth for which languages the app ships: AppLanguage parses it for the
in-app picker (Settings -> App language) and android:localeConfig points
the system per-app language settings at it. So both translations were
compiled into the APK and reachable by nothing — you could not pick either
one, and only a device already set to de/pt-BR would ever have seen them.

Adds the two BCP-47 tags. Note the tags are `de` and `pt-BR` while the
resource folders are values-de and values-pt-rBR; the `r` is an Android
resource-qualifier artefact and must not appear here.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_0146mhMLZ5AqJSZkADDc92Jz

app/src/main/res/xml/locales_config.xml

@@ -8,4 +8,6 @@
 -->
 <locale-config xmlns:android="http://schemas.android.com/apk/res/android">
     <locale android:name="en" />
+    <locale android:name="de" />
+    <locale android:name="pt-BR" />
 </locale-config>