added Mercado Pago integration with new payment handling functions and updated app routing

db/migrations/20260114130200_mp_payments.sql

@@ -0,0 +1,19 @@
+-- migrate:up
+create table if not exists mp_payments (
+  tenant_id uuid not null references tenants(id) on delete cascade,
+  woo_order_id bigint null,
+  preference_id text null,
+  payment_id text null,
+  status text null,
+  paid_at timestamptz null,
+  raw jsonb not null default '{}'::jsonb,
+  created_at timestamptz not null default now(),
+  updated_at timestamptz not null default now(),
+  primary key (tenant_id, payment_id)
+);
+
+create index if not exists mp_payments_tenant_order_idx
+  on mp_payments (tenant_id, woo_order_id);
+
+-- migrate:down
+drop table if exists mp_payments;