## Summary
`packages/core` declared `socket.io`, the server package, but never
imported it. Its only Socket.IO usage is the client:
```
packages/core/src/v3/zodSocket.ts
packages/core/src/v3/runEngineWorker/supervisor/session.ts
import { io } from "socket.io-client";
```
The only occurrence of `socket.io` outside those client imports was the
`package.json` line itself. Since `@trigger.dev/core` is published, that
line meant every consumer installed a server package nothing in the tree
imports.
`socket.io-client` is untouched. `apps/webapp` and `apps/supervisor`
keep their own `socket.io` dependencies, so the server side is
unaffected.
Found with `pnpm run knip:deps`, which the repo already ships.
`pnpm run typecheck` passes across all 57 workspaces, and
`@trigger.dev/core` builds clean.
Stacked on #4639.
nicktrn
d62dd0dc30