a0427be086
Adds 22 DNS e2e subtests across 8 test methods covering: upstream resolution (A, AAAA, multi-A), TCP mode, bypass rules, host mapper, exchange failure (graceful error recovery), rate limiter wiring, invalid query handling, and DNS over TLS (mode: tls). Includes two authoritative DNS responders (UDP/TCP), a standalone DNS query client, and a TLS DNS query script.