Add SMS templates, prepaid IRT billing, and advertising shortcode 9000590009.

Charge ceil(len/64)*400 IRT per recipient across OTP, customer, and partner SMS; seed new businesses with 500k IRT; default partner sends to the advertising line.

Co-authored-by: Cursor <cursoragent@cursor.com>

database/migrations/081_sms_templates.sql

@@ -0,0 +1,36 @@
+-- SMS templates per business (verified by super-admin → Meshkee service shortcode).
+
+CREATE TABLE IF NOT EXISTS sms_templates (
+  id            BIGSERIAL PRIMARY KEY,
+  business_id   BIGINT NOT NULL REFERENCES businesses (id) ON DELETE CASCADE,
+  name          VARCHAR(255) NOT NULL,
+  body          TEXT NOT NULL,
+  is_verified   BOOLEAN NOT NULL DEFAULT FALSE,
+  verified_at   TIMESTAMPTZ NULL,
+  verified_by   BIGINT NULL REFERENCES users (id) ON DELETE SET NULL,
+  created_at    TIMESTAMPTZ NOT NULL DEFAULT now(),
+  updated_at    TIMESTAMPTZ NOT NULL DEFAULT now()
+);
+
+CREATE INDEX IF NOT EXISTS idx_sms_templates_business_id
+  ON sms_templates (business_id);
+
+CREATE INDEX IF NOT EXISTS idx_sms_templates_business_verified
+  ON sms_templates (business_id, is_verified);
+
+CREATE INDEX IF NOT EXISTS idx_sms_templates_created_at
+  ON sms_templates (created_at DESC);
+
+CREATE OR REPLACE FUNCTION sms_templates_set_updated_at()
+RETURNS TRIGGER AS $$
+BEGIN
+  NEW.updated_at = now();
+  RETURN NEW;
+END;
+$$ LANGUAGE plpgsql;
+
+DROP TRIGGER IF EXISTS sms_templates_set_updated_at ON sms_templates;
+CREATE TRIGGER sms_templates_set_updated_at
+  BEFORE UPDATE ON sms_templates
+  FOR EACH ROW
+  EXECUTE FUNCTION sms_templates_set_updated_at();