CLA check failing on sync PR due to co-authored web-based suggestion commits

**This is a Bug Report**

**Problem:**
Weekly sync PR kubernetes/website#55936 (merging `main` into `dev-1.37`) is failing [CLA checks](https://github.com/kubernetes/website/pull/55936#issuecomment-4556884853) due to `Co-authored-by` trailers on commits accepted via GitHub's web-based suggestion flow.

**Root Cause:**
When accepting suggestions via GitHub UI:
- The suggester becomes a co-author with their GitHub email in `Co-authored-by`
- No `--signoff` is added automatically
- EasyCLA validates co-author emails against CLA registration
- Even with correct email matching CLA, the missing signoff causes the check to fail

**Impact:**
- Sync PRs to `dev-1.37` are blocked on CLA checks
- Requires manual CLA re-authorization for each co-author

**Proposed Solution:**
Require sign-off on web-based commits (GitHub feature: https://github.blog/changelog/2022-06-08-admins-can-require-sign-off-on-web-based-commits/)

**Page to Update:**
N/A (this is a repository configuration issue, not content)

cc: @reylejano @kernel-kun

Start by reviewing the linked kubernetes/website#55936 sync PR, its CLA check comment, and GitHub's documented setting for requiring sign-off on web-based commits. Confirm the repository configuration that controls this behavior and verify that a subsequent web-based suggestion commit passes EasyCLA without manual co-author re-authorization.

Written by the indexing model from the issue text.