tenant_channels migration

db/migrations/20260102031918_tenant_channels.sql

@@ -0,0 +1,11 @@
+-- migrate:up
+create table if not exists tenant_channels (
+  tenant_id uuid not null references tenants(id) on delete cascade,
+  channel_type text not null,           -- 'whatsapp'
+  channel_key text not null,            -- e.g. '+5491122334455' or 'PHONE_NUMBER_ID'
+  created_at timestamptz not null default now(),
+  primary key (channel_type, channel_key)
+);
+
+-- migrate:down
+drop table if exists tenant_channels;