fix(server): fall back when the recorded PR base is unavailable remotely#22942

chore(server): register PR evidence harness scripts as knip entries

test(server): add running-server evidence harness for PR base fallback

Merge branch 'main' into fix/issue-22920

fix(server): tolerate optional PR base provider detection failures

Merge branch 'main' into fix/issue-22920

fix(server): recognize target aliases across source control providers

fix(server): validate PR bases on the resolved target remote

fix(server): retain fork PR bases and fallback notices

fix(server): validate recorded PR bases against remote refs