feat: integrate platform backend and application interfaces

server/migrations/0016_v1_message_outbox_leases.sql

@@ -0,0 +1,9 @@
+-- Preserve message outbox lease and provider result metadata across restarts.
+ALTER TABLE IF EXISTS email_sms_outbox
+  ADD COLUMN IF NOT EXISTS lease_owner TEXT,
+  ADD COLUMN IF NOT EXISTS lease_expires_at TIMESTAMPTZ,
+  ADD COLUMN IF NOT EXISTS provider_message_id TEXT,
+  ADD COLUMN IF NOT EXISTS last_error TEXT,
+  ADD COLUMN IF NOT EXISTS updated_at TIMESTAMPTZ NOT NULL DEFAULT now();
+CREATE INDEX IF NOT EXISTS email_sms_outbox_poll_idx
+  ON email_sms_outbox(status, next_attempt_at);