fix(docker+brain): make container Chrome search work, harden, improve toggle

Addresses review findings on the dockerized stack:
- Container Chrome search was dead: add --remote-debugging-port + a non-default
  --user-data-dir (Chrome 136+ refuses CDP on the default profile), add the
  playwright dep (browse-search.mjs connectOverCDP) with browser download
  skipped, and connect to 127.0.0.1 not "localhost" (container localhost -> ::1
  while Chrome binds IPv4). Verified: browse-search returns real results.
- Broadcast toggle reliability: always offer setBroadcast in screen-share mode
  (the embedding/keyword router dropped it for non-English utterances) and make
  its description force a tool call. "방송 꺼줘"->stop now 5/5; no false triggers.
- Stop the broadcast on voice leave (no orphaned stream).
- Security: bind VNC/noVNC to loopback by default (VNC_BIND override) and the
  bridge to the container loopback (BRIDGE_HOST=127.0.0.1), not published.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

bot/scripts/stream-test/browse-search.mjs

@@ -9,6 +9,9 @@
 import { chromium } from 'playwright';
 
 const CDP = process.env.CDP_PORT || '9222';
+// Use 127.0.0.1, not "localhost": in containers localhost can resolve to IPv6
+// (::1) first while Chrome's CDP listens on IPv4, giving ECONNREFUSED ::1.
+const CDP_HOST = process.env.CDP_HOST || '127.0.0.1';
 const query = process.argv[2] || '';
 const mode = (process.argv[3] || 'search').toLowerCase();
 const out = (o) => { process.stdout.write(JSON.stringify(o)); };
@@ -17,7 +20,7 @@ if (!query) { out({ ok: false, error: 'no query' }); process.exit(1); }
 
 let b;
 try {
-  b = await chromium.connectOverCDP(`http://localhost:${CDP}`);
+  b = await chromium.connectOverCDP(`http://${CDP_HOST}:${CDP}`);
   const ctx = b.contexts()[0];
   const page = ctx.pages()[0] || (await ctx.newPage());
   page.setDefaultTimeout(20000);