Lower handoff artifact warnings to debug

[tatoalo]

Problem

Routine handoff artifact size limits are expected behavior but currently appear as warnings to users, adding noise to the visible log stream.

Changes

Lower the artifact-size skip and resulting checkpoint-discard messages from warning to debug level.

[trunk-io]

😎 Merged directly without going through the merge queue, as the queue was empty and the PR was up to date with the target branch - details.

[github-actions]

React Doctor found no issues in the changed files. 🎉

_{Reviewed by React Doctor for commit 1003758.}

[github-actions]

Two warn→debug log level changes with no logic affected. No showstoppers.

[greptile-apps]

_{Reviews (1): Last reviewed commit: "Lower handoff artifact logs to debug" | Re-trigger Greptile}

[greptile-apps]

Unexpected Discards Lose Warning Signal

This branch also runs when required uploads are missing because direct and inline upload attempts failed, not only when an artifact exceeded its expected size limit. Log collectors that exclude debug entries will lose the final checkpoint-discard event and its checkpoint ID, upload state, and artifact sizes, making unexpected checkpoint loss harder to diagnose.

Suggested change

	this.logger.debug(
	"Discarding handoff checkpoint: required artifact uploads did not complete",
	this.logger.warn(
	"Discarding handoff checkpoint: required artifact uploads did not complete",

Note: If this suggestion doesn't match your team's coding style, reply to this and let me know. I'll remember it for next time!