multi tenancy part 1

backend/migrations/20240902011000_create_user_memberships/up.sql

@@ -0,0 +1,12 @@
+CREATE TABLE public.user_memberships (
+    id UUID PRIMARY KEY,
+    user_id UUID NOT NULL REFERENCES users(id) ON DELETE CASCADE,
+    tenant_id UUID NOT NULL REFERENCES public.tenants(tenant_id) ON DELETE CASCADE,
+    role TEXT NOT NULL,
+    created_at TIMESTAMPTZ NOT NULL DEFAULT NOW(),
+    updated_at TIMESTAMPTZ NOT NULL DEFAULT NOW(),
+    UNIQUE (user_id, tenant_id)
+);
+
+CREATE INDEX user_memberships_tenant_id_idx ON public.user_memberships (tenant_id);
+CREATE INDEX user_memberships_user_id_idx ON public.user_memberships (user_id);