Add iteration deletion from `Runpath` to `runconfig`

We should allow users to delete specified iterations (e.g iter-1 and iter-2) from the `Runpath` post evaluation. This should be set via iteration specific checkboxes/list of iterations (CLI). Removing it could reduce amount of space used on the scratch disk, keeping only the necessary files for QC.

Should be opt-in and not opt-out, do not want to risk ruining runs for the users

Start by locating the runconfig CLI handling for Runpath and the post-evaluation lifecycle. Trace how iteration-specific options are parsed and how scratch-disk files are retained, then define completion as an explicit opt-in selection that removes only the requested iterations while preserving necessary QC files.

Written by the indexing model from the issue text.