fix(shopping): filter out __inactive__ sentinel rows on relay

The old single-list clearRemote wrote a dummy row with card_uid
'__inactive__' instead of deleting. After the multi-list migration
that row still exists alongside real lists, causing every list to
appear twice on the phone — once as "all done" (the empty sentinel)
and once with actual items. Filter it out in shoppingLoadAll and
delete it on bootstrap so it doesn't linger.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

relay/inc/bootstrap.php

@@ -271,6 +271,8 @@ if (count($shoppingPk) === 1) {
 } elseif (!in_array('position', $shoppingColNames)) {
     $db->exec('ALTER TABLE shopping_state ADD COLUMN position INTEGER NOT NULL DEFAULT 0');
 }
+// Clean up __inactive__ sentinel rows from the old single-list era.
+$db->exec("DELETE FROM shopping_state WHERE card_uid = '__inactive__'");
 
 // Sync-event notifications: replaces the old bot-chat mechanism. When a
 // client syncs a card they received, they POST here; the sender polls