Enable append-only comments for campaign generator workflow

[Copilot]

The agentic-campaign-generator workflow's message text implied new comments would be created ("post the link + checklist back on this issue when ready"), but the workflow was updating the activation comment instead.

Changes

• Added append-only-comments: true to .github/workflows/agentic-campaign-generator.md messages configuration
• Recompiled workflow to regenerate lock file

Behavior

With append-only-comments: true:

• run-started message creates the initial comment
• run-success/run-failure messages create separate comments
• Each status update is preserved as a distinct comment on the issue

messages:
  append-only-comments: true
  run-started: "### :rocket: Campaign setup started..."
  run-success: "### :white_check_mark: Campaign setup complete..."
  run-failure: "### :x: Campaign setup {status}..."

The setting is handled by notify_comment_error.cjs and update_activation_comment.cjs, which check messagesConfig?.appendOnlyComments to determine whether to create new comments or update existing ones.

Original prompt

Analyze why during campaign generation, message status with append only true still updates the old comment instead of creating a new one, see example here: https://github.com/githubnext/gh-aw/issues/11294

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[mnkiefer]

@copilot This is the derivative. Should be part of generator.go?