fix: restore trailing newline in perf-changelog.yaml (unblocks all changelog sweeps)

[arygupt]

Problem

#1798 merged perf-changelog.yaml without a trailing newline. The no-deletions guard in utils/process_changelog.py then trips on every subsequent changelog PR: appending an entry makes the prior last line gain a newline, which git diff reports as a deleted line → ValueError: Deletions are not allowed.

Evidence: run-only sweep PR #1791 fails setup with exactly this on two runs (27721466065, 27721557297). This blocks all changelog-driven sweeps, not just mine.

Fix

Restore the single trailing newline byte.

⚠️ This PR's own run-sweep check will fail on the same guard (the newline change is itself reported as a deletion). Please admin-merge, or push the newline directly to main.

🤖 Generated with Claude Code

---

Note

Low Risk
Single-byte EOF fix in a changelog file; no runtime or benchmark behavior changes.

Overview
Restores a trailing newline at the end of perf-changelog.yaml after PR #1798 landed the file without one.

Without that byte, any follow-up changelog PR that appends an entry makes git diff show the previous last line as deleted (newline normalization), which triggers ValueError: Deletions are not allowed in utils/process_changelog.py and blocks changelog-driven sweep CI. No benchmark or config content changes—formatting only.

^{Reviewed by Cursor Bugbot for commit 19589a3. Bugbot is set up for automated code reviews on this repo. Configure here.}

[github-actions]

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