[FS] Tune Gmail write confirmation guidance

[Aismit]

Summary

• Update the Gmail skill description so direct write requests require clear intent, not a second confirmation round.
• Clarify that prompts like labeling recruiter cold emails or deleting calendar update emails are explicit user intent once the matching messages are reasonably identified.
• Extend the Gmail label-actions reference with archive/delete tool shapes, cleanup tool choice, and a confirmation boundary for heuristic and broad cleanup flows.

Why

The skill previously used "explicit confirmation" wording around Gmail writes. That could cause the model to ask again even when the current user prompt already clearly requested an action, such as labeling recruiter spam or deleting calendar-update emails.

This change preserves safety for ambiguous or low-confidence matches while letting clear cleanup requests proceed after normal search or inspection.

Plain English

Before, the skill could read "please label these emails" as "ask me again before labeling." Now it reads it as "find the right emails, check that they match, then do what I asked unless the target set is unclear."

Testing

• git diff --check -- plugins/gmail/skills/gmail/SKILL.md plugins/gmail/skills/gmail/references/label-actions.md