ci: skip app.cameleer.io in linkinator (auth host)

CI's lint:links step started failing while app.cameleer.io is in
maintenance — linkinator follows the sign-in/sign-up CTAs out to
the Logto host and surfaces transient 502s as build failures.

The skip list already covered auth.cameleer.io but missed the
app.cameleer.io rename from commit fa12df8. Add it alongside
the other internal hosts.

Trade-off: CI no longer catches a real breakage of the auth URLs.
Acceptable because (a) the auth host has its own deploy gates,
(b) maintenance windows there should not red-bar marketing-site
deploys, (c) the site's middleware/header tests still verify the
URL shape via the auth.test.ts schema.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

linkinator.config.json

@@ -2,6 +2,7 @@
   "recurse": true,
   "silent": true,
   "skip": [
+    "^https://app\\.cameleer\\.io",
     "^https://auth\\.cameleer\\.io",
     "^https://platform\\.cameleer\\.io",
     "^https://www\\.cameleer\\.io",