fix(article-summary): only engage FSM when user explicitly asks for summary/audio

Previously any chat message containing an article URL triggered the
Blinkist FSM: Firecrawl extraction + LLM topic detection + 3-option
menu. Pasting a link as conversational context spammed the menu.

Now _check_for_url additionally requires an intent keyword (summary,
zusammenfassung, audio, mp3, blinkist, tldr, lies das, fasse zusammen,
discuss/diskutieren, etc.) before engaging. Without intent the URL
falls through to the normal AI handler.

Also bind-mount article_summary/ so future fixes survive container
recreate (matches the pattern used for bot.py/voice.py/agent.py).

docker-compose.yml

@@ -36,6 +36,7 @@ services:
       - ./e2ee_patch.py:/app/e2ee_patch.py:ro
       - ./cross_signing.py:/app/cross_signing.py:ro
       - ./device_trust.py:/app/device_trust.py:ro
+      - ./article_summary:/app/article_summary:ro
     depends_on:
       memory-service:
         condition: service_healthy