fix: add German keywords for audio/text summary options (MAT-166)

'Audiozusammenfassung' and 'Textzusammenfassung' now correctly trigger
the audio/text summary flows instead of falling through to regular LLM
which says it can't create audio files.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

article_summary/__init__.py

@@ -243,11 +243,11 @@ class ArticleSummaryHandler:
             return f"__DISCUSS__{title}\n{article_context}"
 
         # Option 2: Text summary — generate and return text, no TTS
-        if body_lower in ("2", "text", "text summary", "zusammenfassung"):
+        if body_lower in ("2", "text", "text summary", "zusammenfassung", "textzusammenfassung"):
             return await self._generate_text_summary(room_id, sender)
 
         # Option 3: Audio summary — enter language selection (existing flow)
-        if body_lower in ("3", "audio", "audio summary"):
+        if body_lower in ("3", "audio", "audio summary", "audiozusammenfassung", "audio zusammenfassung"):
             return self._prompt_language(room_id, sender)
 
         # Anything else — user is just chatting, reset and pass through with article context