Add smart newsletter digest with feedback learning

- Runs daily at 8 PM Australia/Perth time
- Fetches newsletters from past 24 hours via IMAP
- Scores based on learned preferences (topics, sources)
- Summarizes key points and highlights
- Sends digest to Telegram + Gotify
- Learns from user feedback (👍/👎/topic preferences)
- Preferences stored in newsletter-preferences.json

automations/newsletter-digest/newsletter-preferences.json

@@ -0,0 +1,9 @@
+{
+  "liked_topics": ["AI", "machine learning", "productivity", "automation"],
+  "disliked_topics": [],
+  "preferred_sources": ["The Rundown", "AI Valley", "TLDR"],
+  "avoided_sources": [],
+  "preferred_length": "medium",
+  "feedback_count": 0,
+  "last_feedback": null
+}