chore: point every in-tree reference at ai-job-search-dev/ai-job-search (#776)

The repository is moving from the MadsLorentzen personal account to the
ai-job-search-dev organization. GitHub redirects the old slug, but the
upstream-watch guard compares github.repository against the literal slug
and would start running the fork-only triage job on upstream itself, and
the upstream-check tool and its tests pin the slug too. README, CONTRIBUTING,
SECURITY, SETUP, the CI workflow, the issue-template config and the
CHANGELOG links follow.

Co-authored-by: Claude Fable 5.1 <noreply@anthropic.com>

.agents/skills/linkedin-search/cli/tests/fixtures/search-cards.provenance.md

@@ -2,7 +2,7 @@
 
 `search-cards.json` stores the HTML string for the first two verbatim `<li>` cards from a real
 LinkedIn guest search response captured by **portapulito** through the CLI's
-`htmlFetch` on 2026-07-14 and published in [PR #153](https://github.com/MadsLorentzen/ai-job-search/pull/153).
+`htmlFetch` on 2026-07-14 and published in [PR #153](https://github.com/ai-job-search-dev/ai-job-search/pull/153).
 That PR was closed as an accidental personalized-fork submission, not merged.
 
 Source: `.agents/skills/linkedin-search/cli/test/__fixtures__/search-list.html`