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/JohannesKaufmann/html-to-markdown/v2/converter/prioritized.go

@@ -0,0 +1,33 @@
+package converter
+
+import "sort"
+
+const (
+	// PriorityEarly means that the handler will be run **early** in the process.
+	// To run it even earlier you need to subtract from this number.
+	PriorityEarly = 100
+
+	// PriorityStandard is for handlers that don't need to be run in a particular order.
+	PriorityStandard = 500
+
+	// PriorityLate means that the handler will be run **late** in the process.
+	// To run it even later you need to add to this number.
+	PriorityLate = 1000
+)
+
+type prioritizedValue[V any] struct {
+	Value    V
+	Priority int
+}
+
+type prioritizedSlice[V any] []prioritizedValue[V]
+
+func (s prioritizedSlice[V]) Sort() {
+	sort.Slice(s, func(i, j int) bool {
+		return s[i].Priority < s[j].Priority
+	})
+}
+
+func prioritized[V any](v V, priority int) prioritizedValue[V] {
+	return prioritizedValue[V]{v, priority}
+}