savearoundtrip: HTTPS DNS 레코드를 게시하고 왕복 1회를 건너뛰기

By publishing HTTP/3 support directly in HTTPS DNS records, browsers can use QUIC from the first connection, eliminating the round-trip latency penalty of the Alt-Svc header approach. This improvement becomes crucial for web applications where every millisecond matters, and also enables advanced features like Encrypted Client Hello for privacy and IP hints for faster connection establishment.