wip(ci): retire the prerelease pin watch script with its workflow

Claude-Session: https://claude.ai/code/session_01H835wAyqCCeF7jiYq7XSxi
Co-Authored-By: Claude <noreply@anthropic.com>

Author: claude

package.json

@@ -151,7 +151,6 @@
     "check:dev-prereqs": "node scripts/check-dev-prereqs.mjs --self-test && node scripts/check-dev-prereqs.mjs",
     "check:objectui-changeset": "node scripts/objectui-changeset-digest.mjs --self-test && node scripts/objectui-range.mjs --self-test",
     "check:objectui-bump": "bash scripts/bump-objectui.selftest.sh",
-    "check:prerelease-pins": "node scripts/check-prerelease-pin-watch.mjs --self-test && node scripts/check-prerelease-pin-watch.mjs",
     "check:empty-changeset": "node scripts/check-empty-changeset.mjs --self-test && node scripts/check-empty-changeset.mjs",
     "check:adr-0087-registration": "node scripts/check-adr-0087-registration.mjs --self-test && node scripts/check-adr-0087-registration.mjs",
     "check:changeset-gate-self-tests": "node scripts/check-empty-changeset.mjs --self-test && node scripts/check-adr-0087-registration.mjs --self-test && node scripts/check-changeset-no-major.mjs --self-test",