Replace presence schedules with multiple presence patterns per child (schema 9)

A child now carries zero or more home/away presence patterns instead of
at most one schedule. Migration 9 creates presence_patterns, copies every
presence_schedules row across as a 'home' pattern named "Home schedule"
(cycle, anchor and pattern verbatim), and drops the old table in one
transaction. Migration 1 keeps creating the retired table from a frozen
copy of its DDL; schema.py no longer declares it.

PresenceEngine resolves override -> any covering away pattern (absent)
-> any covering home pattern (present) -> otherwise absent when the child
has a home pattern, else present. The home-pattern default keeps every
migrated child's presence unchanged.

The admin plane's one-per-child presence-schedule routes are replaced by
pattern CRUD: GET/POST /children/{child_id}/presence-patterns and
PATCH/DELETE /presence-patterns/{pattern_id}.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

tests/test_api_panel.py

@@ -141,7 +141,7 @@ async def _seed_household(
             [bo.id],
             [("morning", "17:00")],
         )
-        # Today's instances first, while Ada has no presence schedule
+        # Today's instances first, while Ada has no presence pattern
         # (she is present every day, so her instance IS generated).
         await _materialize.materialize(
             database,
@@ -183,12 +183,14 @@ async def _seed_household(
             if record.due_time == "09:00"
         )
 
-        # Ada's custody schedule, added AFTER materialization (the
+        # Ada's custody pattern (one home pattern), added AFTER materialization (the
         # same order test_core_snapshot.py seeds): 2-week cycle
         # anchored yesterday, empty week 0 covers today => absent
         # today; an override returns her on today+2.
-        await _dao_presence.PresenceSchedulesDao(database).upsert_by_child(
+        await _dao_presence.PresencePatternsDao(database).create(
             ada.id,
+            name="Custody",
+            kind="home",
             cycle_length_weeks=2,
             anchor_date=yesterday_iso,
             pattern="|0,1,2,3,4,5,6",