feat(backend): add foundation services and sql idempotency

backend/core-api/src/services/firebase-auth.js

@@ -0,0 +1,13 @@
+import { applicationDefault, getApps, initializeApp } from 'firebase-admin/app';
+import { getAuth } from 'firebase-admin/auth';
+
+function ensureAdminApp() {
+  if (getApps().length === 0) {
+    initializeApp({ credential: applicationDefault() });
+  }
+}
+
+export async function verifyFirebaseToken(token) {
+  ensureAdminApp();
+  return getAuth().verifyIdToken(token);
+}

backend/core-api/src/services/policy.js

@@ -0,0 +1,5 @@
+export function can(action, resource, actor) {
+  void action;
+  void resource;
+  return Boolean(actor?.uid);
+}