Reorder children for panel display order (Feature 03, task 3)

- ChildrenDao.reorder now requires a COMPLETE permutation of the
  children table: partial lists (missing an existing child), unknown
  ids and duplicates are rejected with ValueError before any write,
  inside the existing transaction and connection lock (check and
  write atomic). Empty list is the maximally partial reorder against
  a non-empty table; against an empty table it stays a no-op. The two
  DAO tests that encoded the old permissive semantics (silent no-op
  on empty/unknown) are updated to the new contract.
- children.py gains reorder_children: the Feature 09-facing wrapper,
  which additionally rejects non-integer ids up front (bools and
  floats would silently compare against stored integer ids at the SQL
  layer).
- Business tests: round-trip (active list returns new order), partial/
  unknown/duplicate/non-int rejections with order-unchanged proofs,
  empty-list rejection, and inactive children keeping positions in a
  whole-table permutation. Suite: 866 passed.

custom_components/nestquest/children.py

@@ -236,6 +236,30 @@ async def set_child_active(
     return updated
 
 
+async def reorder_children(
+    database: NestQuestDatabase, ordered_ids: list[int]
+) -> None:
+    """Rewrite the children's panel display order in one transaction.
+
+    ``ordered_ids`` must be a complete permutation of the children
+    table — every child id exactly once.  A partial list (missing an
+    existing child), an unknown id, or a duplicate is rejected with
+    ValueError before any write, so the current order survives a
+    rejected call.  The DAO enforces this inside its own transaction
+    (check and write are atomic under the connection lock); this
+    wrapper additionally rejects non-integer ids up front, since
+    ``bool`` and floats would silently compare against stored integer
+    ids at the SQL layer.
+    """
+    for child_id in ordered_ids:
+        if isinstance(child_id, bool) or not isinstance(child_id, int):
+            raise ValueError(
+                f"ordered_ids must contain only integer child ids, got "
+                f"{child_id!r}"
+            )
+    await ChildrenDao(database).reorder(ordered_ids)
+
+
 async def list_children(
     database: NestQuestDatabase, *, active_only: bool = False
 ) -> list[ChildRecord]: