p1: /v2/scrape, /v1/fetch, auth, CLI, contract tests

Single Fetcher.Fetch on the Guard that holds DenyPrefixes. skipTlsVerification
is ignored. No 502. keys add writes the secret only to --out. Release binary
has no -test-allow-prefix.

vendor/github.com/itchyny/gojq/iter.go

@@ -0,0 +1,49 @@
+package gojq
+
+// Iter is an interface for an iterator.
+type Iter interface {
+	Next() (any, bool)
+}
+
+// NewIter creates a new [Iter] from values.
+func NewIter[T any](values ...T) Iter {
+	switch len(values) {
+	case 0:
+		return emptyIter{}
+	case 1:
+		return &unitIter{value: values[0]}
+	default:
+		iter := sliceIter[T](values)
+		return &iter
+	}
+}
+
+type emptyIter struct{}
+
+func (emptyIter) Next() (any, bool) {
+	return nil, false
+}
+
+type unitIter struct {
+	value any
+	done  bool
+}
+
+func (iter *unitIter) Next() (any, bool) {
+	if iter.done {
+		return nil, false
+	}
+	iter.done = true
+	return iter.value, true
+}
+
+type sliceIter[T any] []T
+
+func (iter *sliceIter[T]) Next() (any, bool) {
+	if len(*iter) == 0 {
+		return nil, false
+	}
+	value := (*iter)[0]
+	*iter = (*iter)[1:]
+	return value, true
+}