Raise Engine.IO minimum to 6.6.10 for published security fixes #5571

socket.io@4.8.4 declares engine.io: ~6.6.0. The current source manifest has the same floor.

GHSA-2gc4-cqfq-p2gv affects Engine.IO >=6.6.0 <6.6.10. The published 6.6.10 release also covers GHSA-gr94-w7qr-f4j3 and GHSA-r635-g3xr-vw7x, which were patched in 6.6.7.

Please raise the runtime dependency minimum to ~6.6.10. This stays on the existing 6.6 release line.

The current range already permits patched releases. Raising the floor would exclude affected releases from the allowed range; existing consumer lockfiles would still need to be refreshed.