Add shareable client reports

[im-anishraj]

Summary

• add public read-only campaign reports at /reports/[shareSlug]
• add report share slugs, enabled/disabled controls, and campaign UI copy/view actions
• show campaign metrics, top keywords, tracked links, and subtle free-plan CampaignCue branding while keeping paid reports unbranded
• document the roadmap update and add report data/unit coverage

Validation

• npm run db:generate
• npm run typecheck
• npm run lint
• npm test
• npm run build
• browser smoke: /templates/dtc-product-link, /reports/smoke-report-shareable-reports, /reports/missing, /dashboard redirect

Closes #11