fix: remove CI failure tracker (references nonexistent CORE CI workflow)

.github/workflows/failure-issue.yml

@@ -1,20 +0,0 @@
-name: CI Failure Tracker
-
-on:
-  workflow_run:
-    workflows: ["CORE CI", ".github/workflows/core-ci.yml"]
-    types: [completed]
-
-jobs:
-  report:
-    if: ${{ github.event.workflow_run.conclusion == 'failure' }}
-    runs-on: ubuntu-latest
-    steps:
-      - uses: actions/github-script@v7
-        with:
-          script: |
-            await github.rest.issues.create({
-              ...context.repo,
-              title: "CI failed: " + context.payload.workflow_run.name,
-              body: context.payload.workflow_run.html_url
-            })