feat(GRO-600): extend reminder scheduler to send SMS alongside email

- Add SMS opt-in fields to clients schema (smsOptIn, smsConsentDate, smsOptOutDate, smsConsentText)
- Add channel column to reminderLogs with per-channel idempotency
- Create SMS service with Telnyx SDK integration and E.164 validation
- Update reminders service to conditionally send SMS to opted-in clients
- Add TCPA opt-out text to SMS reminders
- Graceful degradation: catch SMS errors without blocking email
- Fix: use clients.phone instead of non-existent clients.phoneE164
- Update clients route to expose SMS fields in API
- Add telnyx dependency to API package
- Create database migration 0028_sms_reminders

Co-Authored-By: Paperclip <noreply@paperclip.ing>

apps/api/package.json

@@ -23,6 +23,7 @@
     "node-cron": "^3.0.3",
     "nodemailer": "^6.9.16",
     "stripe": "^22.0.0",
+    "telnyx": "^1.23.0",
 
     "zod": "^4.3.6"
   },