v0.19.13: release: 0.19.13

Fix Blocking code-review mode repeating the same finalization message. The
stateless review judge re-read the run diff every finalization, so a declined
finding on an unchanged diff got re-raised and the model repeated its rebuttal.
The judge now skips an unchanged diff and, on a changed diff, sees the prior
findings so it re-raises only what's still present and unaddressed (#681).