Feature: campaigns:clone — duplicate a campaign for A/B testing

[nifinet]

Problem

For A/B testing, agents need to create 2 identical campaigns with different pitch_settings. Currently requires recreating everything from scratch.

Proposal

overloop campaigns:clone <campaign_id> --name "New name"

Clones: steps, sending config, pitch_settings, personalization_settings. Does NOT clone: enrollments, sourcing, stats.

Agent workflow for A/B:

1. Create campaign A
2. campaigns:clone <A> --name "... v1-community"
3. Update pitch_settings on clone: campaigns:update <clone> --data '{"pitch_settings":{...}}'
4. Link separate sourcing to each