Decouple cross-domain DB queries for per-app database split

Move Ghost membership sync from blog to account service so blog no
longer queries account tables (users, ghost_labels, etc.). Account
runs membership sync at startup and exposes HTTP action/data endpoints
for webhook-triggered syncs and user lookups.

Key changes:
- account/services/ghost_membership.py: all membership sync functions
- account/bp/actions + data: ghost-sync-member, user-by-email, newsletters
- blog ghost_sync.py: stripped to content-only (posts, authors, tags)
- blog webhook member: delegates to account via call_action()
- try_publish: opens federation session when DBs differ
- oauth.py callback: uses get_account_session() for OAuthCode
- page_configs moved from db_events to db_blog in split script

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

account/app.py

@@ -77,6 +77,25 @@ def create_app() -> "Quart":
     app.register_blueprint(register_account_bp())
     app.register_blueprint(register_fragments())
 
+    from bp.actions.routes import register as register_actions
+    app.register_blueprint(register_actions())
+
+    from bp.data.routes import register as register_data
+    app.register_blueprint(register_data())
+
+    # --- Ghost membership sync at startup ---
+    @app.before_serving
+    async def _sync_ghost_membership():
+        from services.ghost_membership import sync_all_membership_from_ghost
+        from shared.db.session import get_session
+        try:
+            async with get_session() as s:
+                await sync_all_membership_from_ghost(s)
+                await s.commit()
+            print("[account] Ghost membership sync complete")
+        except Exception as e:
+            print(f"[account] Ghost membership sync failed (non-fatal): {e}")
+
     return app