Adds handleSearch() to public-gateway.mjs: users add
https://navigate.st/search?q=%s
as their browser's default search engine and typing bare "silentmode.bch"
in the URL bar (which Chromium and Firefox otherwise send to Google as a
search query, since .bch isn't in ICANN's TLD list) arrives here. Native
BNS TLDs (.bch, .p2p, .bit, .nav) 302 to the relay; anything else falls
through to DuckDuckGo so ordinary search still works.
Live on the VPS gateway at /opt/bns-gateway/public-gateway.mjs.
Nginx now proxies location = /search to 127.0.0.1:8700 as well.
Solves: bare "silentmode.bch" in Chrome/Edge went to Google. It now
resolves to the site via the relay in every browser.