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>

package-lock.json

@@ -14,6 +14,7 @@
         "protobufjs": "^8.8.0"
       },
       "devDependencies": {
+        "@evan/opus": "^1.0.3",
         "@sveltejs/vite-plugin-svelte": "^7.3.1",
         "@tsconfig/svelte": "^5.0.8",
         "@types/node": "^26.6.3",
@@ -827,6 +828,13 @@
         "node": ">=18"
       }
     },
+    "node_modules/@evan/opus": {
+      "version": "1.0.3",
+      "resolved": "https://registry.npmjs.org/@evan/opus/-/opus-1.0.3.tgz",
+      "integrity": "sha512-ADfwIad83W1LuiZDNMjDMDNQRsPz8rj5xnDLExhVWTnA5wGJCLntOn12Ir5rxGBqdfo10QhnNVdd2+gXiZ6xCg==",
+      "dev": true,
+      "license": "MIT"
+    },
     "node_modules/@isaacs/fs-minipass": {
       "version": "4.0.1",
       "resolved": "https://registry.npmjs.org/@isaacs/fs-minipass/-/fs-minipass-4.0.1.tgz",