Add unit API and article unitamount/unitSi patch.

Units use the selected company; article PATCH accepts name/unitamount/unitSi.

src/db/unit.js

@@ -0,0 +1,16 @@
+import { getStore } from './store.js';
+
+export async function list(googleAuthId, companyId) {
+    const store = await getStore();
+    return store.unit.list(googleAuthId, companyId);
+}
+
+export async function upsert(googleAuthId, companyId, data) {
+    const store = await getStore();
+    return store.unit.upsert(googleAuthId, companyId, data);
+}
+
+export async function remove(googleAuthId, companyId, si) {
+    const store = await getStore();
+    return store.unit.delete(googleAuthId, companyId, si);
+}