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>

index.html

@@ -3,7 +3,7 @@
   <head>
     <meta charset="utf-8" />
     <meta name="viewport" content="width=device-width, initial-scale=1" />
-    <meta http-equiv="Content-Security-Policy" content="default-src 'self'; script-src 'self'; style-src 'self' 'unsafe-inline'; img-src 'self' data: blob: https: http:; media-src 'self' blob: https: http:; connect-src 'self' https: http: ws: wss:; object-src 'none'; base-uri 'none'; frame-src https://www.youtube-nocookie.com" />
+    <meta http-equiv="Content-Security-Policy" content="default-src 'self'; script-src 'self' 'wasm-unsafe-eval'; style-src 'self' 'unsafe-inline'; img-src 'self' data: blob: https: http:; media-src 'self' blob: https: http:; connect-src 'self' https: http: ws: wss:; object-src 'none'; base-uri 'none'; frame-src https://www.youtube-nocookie.com" />
     <title>mumh5</title>
   </head>
   <body>