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/collapse/whitespace.go

@@ -0,0 +1,79 @@
+package collapse
+
+import (
+	"unsafe"
+)
+
+func byteSliceToString(b []byte) string {
+	/* #nosec G103 */
+	return *(*string)(unsafe.Pointer(&b))
+}
+
+func replaceAnyWhitespaceWithSpace(source string) string {
+	if source == "" {
+		return source
+	}
+
+	// Some performance optimizations:
+	// - If no replacement was done, we return the original slice and dont allocate.
+	// - We batch appends
+	var ret []byte
+	makeIfNeeded := func() {
+		if ret == nil {
+			ret = make([]byte, 0, len(source))
+		}
+	}
+
+	startNormal := 0
+	startMatch := -1
+	for i := 0; i < len(source); i++ {
+		isWhitespace := source[i] == ' ' || source[i] == '\r' || source[i] == '\n' || source[i] == '\t'
+
+		if startMatch == -1 && isWhitespace {
+			// Start of newlines
+			startMatch = i
+			continue
+		} else if startMatch != -1 && isWhitespace {
+			// Middle of newlines
+			continue
+		} else if startMatch != -1 {
+			// Character after the last newline character
+
+			count := i - startMatch
+			if count == 1 && source[startMatch] == ' ' {
+				// There was only one `isWhitespace` match & that is a space.
+				// So the replacement would be exactly the same...
+			} else {
+				makeIfNeeded()
+				ret = append(ret, source[startNormal:startMatch]...)
+				ret = append(ret, byte(' '))
+				startNormal = i
+			}
+
+			startMatch = -1
+		}
+	}
+
+	if startMatch == -1 && startNormal == 0 {
+		// a) no changes need to be done
+	} else if startMatch == -1 {
+		// b) Only the normal characters until the end still need to be added
+		makeIfNeeded()
+		ret = append(ret, source[startNormal:]...)
+	} else if ret == nil && len(source)-startMatch == 1 && source[startMatch] == ' ' {
+		// c) There is a match, but it is exactly the same as the replacement
+		//    If there is no new slice, we can skip the replacement.
+	} else {
+		// d) The match still needs to be replaced (and possible the previous normal characters be added)
+		makeIfNeeded()
+		ret = append(ret, source[startNormal:startMatch]...)
+		ret = append(ret, byte(' '))
+	}
+
+	if ret == nil {
+		// Huray, we did not do any allocations with make()
+		// and instead just return the original slice.
+		return source
+	}
+	return byteSliceToString(ret)
+}