feat(lagoon): per-query collation for OrderBy, drop the database locale check

- lagoon.OrderBy takes variadic lagoon.OrderOption values; lagoon.Collate(name)
  emits a validated, double-quoted COLLATE clause (e.g. "pl-x-icu")
- remove the exported CheckLocale and the ICU pl-PL check from Open and Use
- framework test containers and per-test databases are plain PostgreSQL
- lagoon README, root README and docs pages drop the locale requirement;
  queries-and-pagination gains a "Sorting with a collation" section
  backed by ExampleCollate

modules/lagoon/attach/lifecycle_test.go

@@ -275,9 +275,6 @@ func attachGorm(t *testing.T) *gorm.DB {
 		postgres.WithUsername("attach"),
 		postgres.WithPassword("attach"),
 		postgres.BasicWaitStrategies(),
-		testcontainers.WithEnv(map[string]string{
-			"POSTGRES_INITDB_ARGS": "--locale-provider=icu --icu-locale=pl-PL --encoding=UTF8",
-		}),
 	)
 	if err != nil {
 		t.Fatalf("postgres: %v", err)