Fix verification retest

We go back over every finding in the previous report and check whether the fix holds. We reopen whatever is still exploitable.

What it includes

Re-running the original proof of concept, finding by finding.
Checking that the fix cannot be walked around another way: a filter is not a patch.
Spotting what has appeared while fixing, which happens more often than it seems.
We start from the scope already known, without repeating discovery.