Align store calls with selected-company scoping and add entity numbers.

Drop companyId from company-scoped store wrappers and routes, add GET /entity/next-number plus optional number on entity create/update, and document dashdbschema API.md lookup in sibling-repos.

src/db/category.js

@@ -1,8 +1,8 @@
 import { getStore } from './store.js';
 
-export async function getTreeForCompany(googleAuthId, companyId) {
+export async function getTreeForCompany(googleAuthId) {
     const store = await getStore();
-    return store.category.getTreeForCompany(googleAuthId, companyId);
+    return store.category.getTreeForCompany(googleAuthId);
 }
 
 export async function createUnderParent({ googleAuthId, parentId, name }) {