guestlink v1: self-hosted guest line (Cleanfeed replacement)

Go + Pion + libopus. One guest, live audio both ways, anonymous chat.
README for this version was not preserved; see the next commit.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

web/index.html

@@ -0,0 +1,5 @@
+<!doctype html>
+<html lang="en"><head><meta charset="utf-8"><meta name="viewport" content="width=device-width,initial-scale=1">
+<title>MMO Guest Line</title><link rel="stylesheet" href="/static/style.css"></head>
+<body><main class="narrow"><h1>MMO Guest Line</h1>
+<p class="muted">You need a personal invite link from the host to join a show.</p></main></body></html>