Add upcoming_entries_for_container to CalendarService

New paginated query for upcoming confirmed entries across all calendars
belonging to a container (page). Used by the events page summary view.

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

services/calendar_impl.py

@@ -239,6 +239,35 @@ class SqlCalendarService:
         merged = sorted(entries_by_id.values(), key=lambda e: e.start_at or period_start)
         return [_entry_to_dto(e) for e in merged]
 
+    async def upcoming_entries_for_container(
+        self, session: AsyncSession, container_type: str, container_id: int,
+        *, page: int = 1, per_page: int = 20,
+    ) -> tuple[list[CalendarEntryDTO], bool]:
+        """Upcoming confirmed entries across all calendars for a container."""
+        cal_ids = select(Calendar.id).where(
+            Calendar.container_type == container_type,
+            Calendar.container_id == container_id,
+            Calendar.deleted_at.is_(None),
+        ).scalar_subquery()
+
+        offset = (page - 1) * per_page
+        result = await session.execute(
+            select(CalendarEntry)
+            .where(
+                CalendarEntry.calendar_id.in_(cal_ids),
+                CalendarEntry.state == "confirmed",
+                CalendarEntry.deleted_at.is_(None),
+                CalendarEntry.start_at >= func.now(),
+            )
+            .order_by(CalendarEntry.start_at.asc())
+            .limit(per_page)
+            .offset(offset)
+            .options(selectinload(CalendarEntry.calendar))
+        )
+        entries = result.scalars().all()
+        has_more = len(entries) == per_page
+        return [_entry_to_dto(e) for e in entries], has_more
+
     async def associated_entries(
         self, session: AsyncSession, content_type: str, content_id: int, page: int,
     ) -> tuple[list[CalendarEntryDTO], bool]: