fix(usernames): sync index active collectible aliases

deploy/migrations/0160_peer_username_search.down.sql

@@ -0,0 +1 @@
+DROP INDEX IF EXISTS public.peer_usernames_active_search_idx;

deploy/migrations/0160_peer_username_search.up.sql

@@ -0,0 +1,6 @@
+-- Active usernames are searched by peer type and a case-normalized prefix.
+-- text_pattern_ops keeps the lookup indexable even when the database collation
+-- cannot use a regular btree index for LIKE 'prefix%'.
+CREATE INDEX peer_usernames_active_search_idx
+    ON public.peer_usernames (peer_type, username_lower text_pattern_ops, peer_id)
+    WHERE active;