gh repo fork --clone - SETUP.md's own fork command - sets the upstream
repo as gh's default repository, which gh uses for creating issues and
PRs. A user's own automation running gh issue create from a fork clone
therefore published personal job-search data on the upstream public
tracker. SETUP.md section 2 now includes gh repo set-default in the fork
commands with a point-of-decision warning, and .github/ISSUE_TEMPLATE/
carries the same heads-up the PR template already had for the web path.
Blank issues stay enabled.
