feat(ingest): downstream claude-email high-conversion email copywriting skill

[harshsinghmp]

Classification

actionable-feature

Context & Rationale

AgriciDaniel/claude-email provides conversion-tested email copywriting frameworks (cold outreach, onboarding sequences, reactivation, win-back) grounded in deliverability best practices.

Scope & Ingestion Plan

1. Ingest upstream from https://github.com/AgriciDaniel/claude-email.
2. Place into skills/marketing/claude-email.
3. Register in skills.manifest.json under Growth, Marketing & Social.

Verification Criteria

• skills/marketing/claude-email/SKILL.md exists and passes manifest schema validation.
• Registered in skills.manifest.json.
• Validated via bun test.