Fix AP blueprint cross-DB queries + harden Ghost sync init

AP blueprints (activitypub.py, ap_social.py) were querying federation
tables (ap_actor_profiles etc.) on g.s which points to the app's own DB
after the per-app split. Now uses g._ap_s backed by get_federation_session()
for non-federation apps.

Also hardens Ghost sync before_app_serving to catch/rollback on failure
instead of crashing the Hypercorn worker.

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

blog/bp/blog/routes.py

@@ -49,6 +49,8 @@ def register(url_prefix, title):
     async def init():
       from .ghost.ghost_sync import sync_all_content_from_ghost
       from sqlalchemy import text
+      import logging
+      logger = logging.getLogger(__name__)
 
       # Advisory lock prevents multiple Hypercorn workers from
       # running the sync concurrently (which causes PK conflicts).
@@ -60,9 +62,18 @@ def register(url_prefix, title):
         try:
             await sync_all_content_from_ghost(s)
             await s.commit()
+        except Exception:
+            logger.exception("Ghost sync failed — will retry on next deploy")
+            try:
+                await s.rollback()
+            except Exception:
+                pass
         finally:
-            await s.execute(text("SELECT pg_advisory_unlock(900001)"))
-            await s.commit()
+            try:
+                await s.execute(text("SELECT pg_advisory_unlock(900001)"))
+                await s.commit()
+            except Exception:
+                pass  # lock auto-releases when session closes
 
     @blogs_bp.before_request
     def route():