chore(gateway): pnpm 11 build-script approvals (allowBuilds) for native voice deps

pnpm 11.17 mengabaikan field pnpm.onlyBuiltDependencies di package.json.
Native deps voice (@discordjs/opus, @lng2004/node-datachannel, zeromq, dll)
tidak pernah kebangun di Nix store karena flake pnpmInstall pakai
--ignore-scripts dan pnpm rebuild tanpa approval. Hasil: receiver/rekaman/
GoLive diam-diam tanpa decoder/encoder native.

pnpm approve-builds --all menulis allowBuilds:true per package di
pnpm-workspace.yaml (harus tracked — flake source cuma ikut file git).
node-crc tetap gagal build (MSRV cargo:: check) tapi tidak pernah
di-import di source — harmless.

services/discord-gateway/pnpm-workspace.yaml

@@ -0,0 +1,18 @@
+allowBuilds:
+  "@discordjs/opus": true
+  "@lng2004/node-datachannel": true
+  esbuild: true
+  node-av: true
+  node-crc: true
+  sharp: true
+  zeromq: true
+# pnpm 11 requires build-script approvals here (the legacy `pnpm` field in
+# package.json is ignored). Native voice deps need their postinstall build.
+onlyBuiltDependencies:
+  - "@discordjs/opus"
+  - "@lng2004/node-datachannel"
+  - esbuild
+  - node-av
+  - node-crc
+  - sharp
+  - zeromq