Built-in Opus codec for browsers without one; cameras on by default with per-person hide

- libopus in WebAssembly takes over voice where WebCodecs audio is missing
  (Firefox on Android); tested for tone, timing and bitrate, and in a browser
  forced onto it
- Cameras in the channel show by themselves once the IP note was confirmed;
  a person's camera can be hidden from the right-click menu, all of them with
  one button; an enlarged camera leaves its tile
- CSP allows wasm-unsafe-eval for the codec

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

THIRD_PARTY_NOTICES.md

@@ -41,3 +41,11 @@ SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
 Runtime and build dependencies (Electron, Svelte, protobufjs, node-forge, DOMPurify and
 others) are distributed under their own licenses, found in each package under `node_modules/`.
+
+## @evan/opus and libopus
+
+The Opus codec compiled to WebAssembly (`opus.wasm`), used for voice in browsers that have no
+audio codec of their own. The package is MIT licensed, Copyright (c) 2021-present evanwashere.
+libopus is under the three-clause BSD license, Copyright 2001-2011 Xiph.Org, Skype Limited,
+Octasic, Jean-Marc Valin, Timothy B. Terriberry, CSIRO, Gregory Maxwell, Mark Borgerding,
+Erik de Castro Lopo.