chore: campaign generation cleanup

[mnkiefer]

• Removes the campaign dispatcher agent file (agentic-campaigns.agent.md) from the repository.
• Updates handling of the agentic campaign generator workflow:
  • Markdown source for the campaign generator is now consistently stored in .github/workflows.
  • Special-case path handling for these files has been removed.

[mnkiefer]

@copilot Fix lint errors

[Copilot]

@mnkiefer I've opened a new pull request, #10742, to work on those changes. Once the pull request is ready, I'll request review from you.