docs: comprehensive documentation for HAN-387

- README.md: full project overview, installation, quick start, CLI reference,
  output format descriptions, architecture overview, and dnstraverse comparison
- GoDoc: package-level documentation for traverse, dns, config, output, and
  fingerprint packages
- GoDoc: TraverserConfig and TraversalResult type comments in traverser.go

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
Co-authored-by: multica-agent <github@multica.ai>

internal/fingerprint/fingerprint.go

@@ -1,3 +1,10 @@
+// Package fingerprint identifies DNS server software by querying the
+// version.bind name in the CHAOS class.  Many authoritative and recursive DNS
+// servers respond with a version string (e.g. "BIND 9.18.1-1") that can be
+// used to identify the software and version in use.
+//
+// Queries are cached per server IP so that repeated lookups within a single
+// traversal run do not incur extra network round-trips.
 package fingerprint
 
 import (