ci: update @latest tag to include agent input

[anntnzrb]

Problem

docs-update.yml shows warnings:

Unexpected input(s) 'agent', valid inputs are ['model', 'share', 'prompt', 'use_github_token']

Cause

@latest points to github-v1.2.1 (Dec 16), but agent input was added in github-v1.2.5 (Dec 20).

New tags don't trigger publish-github-action.yml because GITHUB_TOKEN pushes can't trigger other workflows.

Fix

Immediate: Run publish-github-action.yml via workflow_dispatch.

Long-term: Consider merging release + publish into one workflow to avoid this in the future.