perf(golive): drop @dank074/discord-video-stream — node_modules 1.5GB → 423MB

Remove the last heavy GoLive dependency now that src/goLive/ replaces it:
- @dank074/discord-video-stream (pulled in @lng2004/node-datachannel
  771MB, node-av 118MB + @seydx/node-av-linux-x64 167MB, zeromq 21MB,
  fluent-ffmpeg 13MB — ~1.09GB total)
- onlyBuiltDependencies: drop node-av/zeromq/@lng2004 (keep opus/esbuild/sharp)
- pnpm.lock regenerated; orphan .pnpm dirs removed locally
- @discordjs/opus prebuild: rebuilt binary copied into
  prebuild/node-v127-napi-v3-linux-x64-glibc-2.39/ (node-pre-gyp find path)

Verified: tsc 0 errors, vitest 8/8, biome clean, opus encode OK.
Fresh CI install now ~423MB instead of ~1.5GB.

services/discord-gateway/package.json

@@ -7,11 +7,8 @@
   "pnpm": {
     "onlyBuiltDependencies": [
       "@discordjs/opus",
-      "@lng2004/node-datachannel",
       "esbuild",
-      "node-av",
-      "sharp",
-      "zeromq"
+      "sharp"
     ]
   },
   "scripts": {
@@ -24,7 +21,6 @@
     "test": "vitest run"
   },
   "dependencies": {
-    "@dank074/discord-video-stream": "6.0.0",
     "@discordjs/opus": "^0.10.0",
     "@discordjs/voice": "^0.19.2",
     "@snazzah/davey": "^0.1.11",