fix(ci): retry Danger.js on transient GitHub API fetch errors (#22151)

## Problem

The `danger-js` job in **CI Utils** has been failing across most PRs.
The failure is not a real Danger violation — it's a transient network
error fetching the PR diff/commits from the GitHub API:

```
Failed to fetch GitHub pull request files: FetchError: Invalid response body while trying to fetch
https://api.github.com/repos/twentyhq/twenty/pulls/XXXXX/files?page=1&per_page=100: Premature close
    at Gunzip.<anonymous> (.../node_modules/node-fetch/lib/index.js:400:12)
  errno: 'ERR_STREAM_PREMATURE_CLOSE',
  code: 'ERR_STREAM_PREMATURE_CLOSE'
```

GitHub closes the gzipped HTTP response mid-stream, and Danger's bundled
`node-fetch` has **no retry** on a dropped connection — so any single
blip fails the whole check.

## Why is this happening now?

Nothing on our side changed at the boundary where failures started. The
Node 24.16 bump landed Jun 8 (the job stayed green for 2+ weeks after),
Danger has been pinned at `13.0.4` for months, and there are **zero
commits** to `.nvmrc`, `twenty-utils/package.json`, or the
`yarn-install` action since Jun 22.

What changed is GitHub's API reset rate, and it changed abruptly:

| Day | Failures | Successes | Failure rate |
|-----|----------|-----------|--------------|
| Jun 23 | 1 | 48 | ~2% (green) |
| Jun 24 | 38 | 204 | ~16% |
| Jun 25 | 23 | 25 | **~48%** |

The same PR passes on one run and fails on the next (e.g. one PR shows
up as both pass and fail; another failed 3 runs in a row) — a code bug
can't flip outcomes on identical input, only an infrastructure flake
can. When GitHub's connection-reset rate was ~0% we never noticed; now
that it's in the tens of percent, roughly half of all PRs trip it.

## Fix

Wrap the Danger invocation in a small retry loop (3 attempts, 5s
backoff) so the check absorbs these transient fetch errors instead of
red-flagging the PR. Applied to both the `danger-js` and `congratulate`
jobs since they share the same failure mode.

This is the correct mitigation rather than a code revert — there's no
change on our side to revert. 3 attempts drop a ~48% single-shot failure
rate to ~11%, and a less-degraded ~16% rate to well under 1%. If
GitHub's reliability recovers, the retries simply stop firing and cost
nothing.

This is a CI-only change — no application code is touched.

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.github/workflows/ci-utils.yaml

@@ -29,7 +29,22 @@ jobs:
       - name: Install dependencies
         uses: ./.github/actions/yarn-install
       - name: Utils / Run Danger.js
-        run: cd packages/twenty-utils && npx nx danger:ci
+        # Danger's bundled node-fetch intermittently fails to decode gzipped
+        # GitHub API responses with ERR_STREAM_PREMATURE_CLOSE. Retry to absorb
+        # those transient fetch errors instead of failing the whole check.
+        run: |
+          cd packages/twenty-utils
+          for attempt in 1 2 3; do
+            if npx nx danger:ci; then
+              exit 0
+            fi
+            if [ "${attempt}" -lt 3 ]; then
+              echo "Danger.js attempt ${attempt} failed, retrying in 5s..."
+              sleep 5
+            fi
+          done
+          echo "Danger.js failed after 3 attempts"
+          exit 1
         env:
           DANGER_GITHUB_API_TOKEN: ${{ github.token }}
 
@@ -42,6 +57,19 @@ jobs:
       - name: Install dependencies
         uses: ./.github/actions/yarn-install
       - name: Run congratulate-dangerfile.js
-        run: cd packages/twenty-utils && npx nx danger:congratulate
+        # Same transient ERR_STREAM_PREMATURE_CLOSE protection as danger-js.
+        run: |
+          cd packages/twenty-utils
+          for attempt in 1 2 3; do
+            if npx nx danger:congratulate; then
+              exit 0
+            fi
+            if [ "${attempt}" -lt 3 ]; then
+              echo "Danger.js congratulate attempt ${attempt} failed, retrying in 5s..."
+              sleep 5
+            fi
+          done
+          echo "Danger.js congratulate failed after 3 attempts"
+          exit 1
         env:
           DANGER_GITHUB_API_TOKEN: ${{ secrets.GITHUB_TOKEN }}