feat: add 23 marketing skills from coreyhaines31/marketingskills
Added marketing skills for:
- CRO: page-cro, signup-flow-cro, onboarding-cro, form-cro, popup-cro, paywall-upgrade-cro
- Content: copywriting, copy-editing, email-sequence
- SEO: seo-audit, programmatic-seo, schema-markup, competitor-alternatives
- Paid: paid-ads, social-content
- Growth: referral-program, launch-strategy, free-tool-strategy
- Analytics: ab-test-setup, analytics-tracking
- Strategy: pricing-strategy, marketing-ideas, marketing-psychology
Total skills now: 179
License: MIT
Source: https://github.com/coreyhaines31/marketingskills
e8ad28df0d