nixpacks strategy mixes dockerode and raw docker CLI via execSync

[Alimedhat000]

Summary

packages/worker/src/deployments/strategies/nixpacks.ts:109-125 shells out to docker create / docker cp / docker rm via execSync, while the rest of the worker uses dockerode through DockerRunner.

Why it matters

• Two ways of talking to Docker makes the code harder to follow.
• Raw execSync paths are not mockable in tests the way DockerRunner is.

Fix

Route the static-asset copy through DockerRunner (or add a method for create/cp/rm) so all Docker interaction goes through one abstraction.