bootstrap

chore: remove retired PR skills — superseded by Plex + pr-master

chore: drop local test-writing skill — now bundled in pr-master@sshanzel

chore: consume pr-master@sshanzel from the hub; drop local copies

fix(deps): bump qs to ^6.15.2 to patch GHSA-q8mj-m7cp-5q26

fix(deps): bump axios to ^1.16.0 to patch ReDoS (GHSA-hfxv-24rg-xrqf)