feat: production email (Resend) + offsite backup (B2)

Resend mail transport:
- composer require resend/resend-laravel (v1.4)
- Laravel 11 ships the 'resend' mailer config in config/mail.php + services
- To switch to production email: set MAIL_MAILER=resend + RESEND_API_KEY,
  register the domain at resend.com/domains, and add the TXT + DKIM CNAME
  records in Cloudflare. .env.example documents the required steps.

Backblaze B2 offsite backup:
- New filesystems 'b2' disk (S3-compatible, env: B2_KEY/SECRET/BUCKET/REGION/ENDPOINT)
- BackupAllTenantsCommand: after writing each tenant's zip to local disk, it
  uploads the same file to the b2 disk under {YYYY-MM-DD}/{slug}.zip — only
  when both B2_KEY and B2_BUCKET are set, so unconfigured installs are no-op
- Without offsite, backups live on the same VPS as production: a single
  hardware failure loses everything. B2 + Resend together make the install
  genuinely production-ready (people get email + offsite backup).

Tests (2 new):
- backup uploads to b2 (fake disk) when configured
- backup skips offsite when env vars not present

Full suite: 140 passed. Force-rebuild deploy required so composer install
picks up resend/resend-php.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

.env.example

@@ -48,7 +48,10 @@ REDIS_DB=0
 # Broadcasting (Reverb — adăugăm la nevoie)
 BROADCAST_CONNECTION=log
 
-# Mail — Mailpit intern
+# Mail — Mailpit intern (dev) sau Resend (prod)
+# Dev: lasă smtp + Mailpit. Prod: setează MAIL_MAILER=resend + RESEND_API_KEY,
+# înregistrează domeniul în https://resend.com/domains și adaugă DNS-urile
+# (TXT + DKIM CNAME-uri) în Cloudflare. Verifică în dashboard înainte de trafic.
 MAIL_MAILER=smtp
 MAIL_HOST=autocrm-mailpit
 MAIL_PORT=1025
@@ -58,6 +61,9 @@ MAIL_ENCRYPTION=null
 MAIL_FROM_ADDRESS="noreply@service.mir.md"
 MAIL_FROM_NAME="${APP_NAME}"
 
+# Resend API — necesar dacă MAIL_MAILER=resend
+RESEND_API_KEY=
+
 # Web Push (VAPID) — generate with: php artisan push:vapid
 VAPID_SUBJECT=mailto:admin@service.mir.md
 VAPID_PUBLIC_KEY=
@@ -69,6 +75,15 @@ VAPID_PRIVATE_KEY=
 HEALTH_ALERT_BOT_TOKEN=
 HEALTH_ALERT_CHAT_ID=
 
+# Backblaze B2 (S3-compatible) — offsite backup target for backup:tenants.
+# Creează un bucket privat + Application Key cu acces la el. Fără aceste env
+# vars, backup-urile rămân doar pe VPS (single point of failure).
+B2_KEY=
+B2_SECRET=
+B2_BUCKET=
+B2_REGION=us-west-002
+B2_ENDPOINT=https://s3.us-west-002.backblazeb2.com
+
 # Storage — local pentru MVP, S3-compatible mai târziu
 FILESYSTEM_DISK=local