CLI journey orchestration commands for multi-step email sequences

Features

• CLI journey orchestration commands for multi-step email sequences
• CLI audience segmentation commands for targeted sends
• CLI outcome tracking commands to measure campaign results
• Inbound email authentication — SPF, DKIM, and DMARC verification on incoming mail
• Domain warmup system with automatic per-domain send throttling
• DMARC report monitoring — parser, storage, and API for deliverability insights

Fixes

• Landing page copy updated to mailbox-first framing across hero, problem, and pipeline sections