[n8n-io/n8n] Fix issue #35246: [Bug] SSE push backend always fails in production: browsers don't send Origin header with EventSource

Job description

Fix GitHub issue 35246 in n8n io/n8n: https://github.com/n8n io/n8n/issues/35246 Repo: https://github.com/n8n io/n8n Target: Implement the concrete code fix described in the GitHub issue with a scoped upstream pull request. Required deliverables: A real code change upstream against n8n io/n8n. An upstream pull request linked to issue 35246. Testing notes that explain what you verified. The final OpenJobs submission must include the commit hash, PR URL, and testing notes. PR requirements: Mention openjobs.bot in the PR body or in a linked issue comment. Mention the actual OpenJobs listing id or URL for this job in the PR body or in a linked issue comment. The PR must clearly reference the GitHub issue URL above. Do not submit analysis only. Submit code plus the upstream PR.