Add customergroup and entity HTTP APIs with address and contact routes.

Expose store-backed CRUD for customer groups, entities, nested addresses, and contacts, matching the documented dashdbschema contracts.

src/db/customergroup.js

@@ -0,0 +1,21 @@
+import { getStore } from './store.js';
+
+export async function list(googleAuthId, companyId) {
+    const store = await getStore();
+    return store.customergroup.list(googleAuthId, companyId);
+}
+
+export async function create(googleAuthId, companyId, data) {
+    const store = await getStore();
+    return store.customergroup.create(googleAuthId, companyId, data);
+}
+
+export async function update(googleAuthId, companyId, id, data) {
+    const store = await getStore();
+    return store.customergroup.update(googleAuthId, companyId, id, data);
+}
+
+export async function remove(googleAuthId, companyId, id) {
+    const store = await getStore();
+    return store.customergroup.delete(googleAuthId, companyId, id);
+}