feat(auth): enable cross-domain SSO via shared cookies on .mana.how

- Configure Better Auth with crossSubDomainCookies for .mana.how domain
- Add COOKIE_DOMAIN environment variable (production: .mana.how)
- Sync trustedOrigins with all production subdomains
- Users now login once and are authenticated across all apps

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

docker-compose.macmini.yml

@@ -94,6 +94,8 @@ services:
       JWT_PUBLIC_KEY: ${JWT_PUBLIC_KEY:-}
       JWT_PRIVATE_KEY: ${JWT_PRIVATE_KEY:-}
       BASE_URL: https://auth.mana.how
+      # Cross-domain SSO: share session cookies across all *.mana.how subdomains
+      COOKIE_DOMAIN: .mana.how
       SMTP_HOST: smtp-relay.brevo.com
       SMTP_PORT: 587
       SMTP_USER: ${SMTP_USER:-94cde5002@smtp-brevo.com}