perf(savedMessages): save a db lookup and message content decryption by building the returned entity manually after creation

backend/src/data/buildEntity.ts

@@ -0,0 +1,7 @@
+export function buildEntity<T extends any>(Entity: new () => T, data: Partial<T>): T {
+  const instance = new Entity();
+  for (const [key, value] of Object.entries(data)) {
+    instance[key] = value;
+  }
+  return instance;
+}