cli: add up --recreate as an alias for --remove-existing-container #76

The library field is `UpOptions.Recreate`. The CLI currently exposes only `--remove-existing-container` (upstream `@devcontainers/cli` naming) for it.

Add a shorter `--recreate` alias to match our own naming. Keep `--remove-existing-container` for muscle memory from upstream users.

Both should map to the same bool — define one, alias via cobra.