feat(cover): filter obituaries from cover headlines

Exclude articles categorized as "Obituaries" from the headline list
passed to cover generation. Applied in all three call sites: manual
publish, issue regenerate, and auto-publish scheduler.

Made-with: Cursor

src/scheduler.py

@@ -76,7 +76,10 @@ class SchedulerManager:
                 return
 
             article_ids = [a.id for a in articles]
-            headlines = [a.title for a in articles]
+            headlines = [
+                a.title for a in articles
+                if "Obituaries" not in json.loads(a.categories)
+            ]
 
             categories_list = []
             for a in articles: