fix(setup): stop fork clones from filing issues on the upstream repo by default (#389) (#392)

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.

.github/ISSUE_TEMPLATE/bug-report.md

@@ -0,0 +1,22 @@
+---
+name: Bug report or improvement
+about: A defect or improvement in the framework itself — not your personal job search
+---
+
+<!-- Heads-up before you file: if you are working in a personalized fork,
+     note that the gh CLI points issue creation at this UPSTREAM repo by
+     default (`gh repo fork --clone` sets it as the default repository).
+     Personal application tracking, job evaluations, and incident logs
+     belong in YOUR fork or private repo - this tracker is public. Run
+     `gh repo set-default <your-username>/ai-job-search` in your clone to
+     keep your own automation pointed home (SETUP.md, section 2). -->
+
+## Description
+
+## Steps to Reproduce
+
+## Expected Behavior
+
+## Actual Behavior
+
+## Impact