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/config.yml

@@ -0,0 +1,9 @@
+blank_issues_enabled: true
+contact_links:
+  - name: Filing from a personalized fork? Read this first
+    url: https://github.com/MadsLorentzen/ai-job-search/blob/master/SETUP.md#2-fork-and-clone
+    about: >-
+      The gh CLI in a fork clone targets THIS public repo by default. Personal
+      application tracking, evaluations, and incident logs belong in your own
+      fork or private repo — run `gh repo set-default <you>/ai-job-search`
+      there to keep your automation pointed home.