post-completion flow: survey, referral program, review ask

- Migration 081: referral_codes, referral_uses, exit_surveys tables
- API: POST /api/v1/survey, POST /api/v1/referral/check, GET /api/v1/referral/:email
- Worker: completion_emails.py — sends completion + 24h follow-up (survey + referral)
- Survey page: /survey/?order=X&rating=N — star rating, feedback, Google review ask
- Referral: REF-FIRSTNAME codes, $25 credit per referred order, no limit
- Low ratings (1-3 stars) trigger Telegram alert for admin follow-up
- Cron: every 15 minutes

infra/ansible/roles/worker-crons/defaults/main.yml

@@ -134,6 +134,14 @@ worker_crons:
     on_calendar: "*-*-* 08:00:00 UTC"
     persistent: true
 
+  # Post-completion emails — every 15 minutes.
+  # Sends completion confirmations + 24h follow-up (survey + referral).
+  - name: pw-completion-emails
+    description: Send post-completion and follow-up emails
+    module: scripts.workers.completion_emails
+    on_calendar: "*-*-* *:0/15:00 UTC"
+    persistent: false
+
   # Florida entity downloader — daily 07:30 UTC.
   # Downloads daily diffs from FL Sunbiz SFTP (free public access).
   - name: pw-fl-entity-downloader