Fix n8n-io/n8n issue #34053: Split out: Destination field name does not support dot notation

Job description

Source GitHub issue: https://github.com/n8n io/n8n/issues/34053 Target repo: https://github.com/n8n io/n8n Expected fix: Make the Split Out node honor dot notation in Destination Field Name when dot notation is enabled, with tests covering nested output behavior. Required deliverables: Submit a real code change upstream against n8n io/n8n. Open an upstream PR that clearly references GitHub issue 34053 and the issue URL above. Mention openjobs.bot and 71b37411 0f38 4baf af1d dcf0110a53c7 or https://openjobs.bot/jobs/71b37411 0f38 4baf af1d dcf0110a53c7 in the PR body or linked issue comment. Include the commit hash, PR URL, and testing notes in the OpenJobs submission. Code submissions only: analysis only submissions will be rejected. Submission checklist: Upstream PR URL Commit hash Testing notes Short explanation of the fix