The setting `settings.platform_domain` (the global/main domain like "wizard.lu")
was easily confused with `platform.domain` (per-platform domain like "rewardflow.lu").
Renamed to `settings.main_domain` / `MAIN_DOMAIN` env var across the entire codebase.
Also updated docs to reflect the refactored store detection logic with
`is_platform_domain` / `is_subdomain_of_platform` guards.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
Step 25 in Hetzner docs with full Google Cloud/Wallet Console setup,
service account configuration, local testing, and architecture diagrams.
Loyalty module env vars added to environment.md and .env.example.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
SendGrid handles both transactional emails and marketing campaigns
under one account. Updated alertmanager SMTP placeholders, hetzner
setup guide (Step 19.5), and environment reference to recommend
SendGrid as the primary email provider.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>