refactor(desktop): organize lib modules by domain

apps/desktop/src/lib/metadata/schemaTreeCache.ts

@@ -0,0 +1,41 @@
+export const SCHEMA_TREE_CACHE_TTL_MS = 15 * 60 * 1000;
+
+export interface SchemaTreeCacheEnvelope<T> {
+  version: 2;
+  cachedAt: string;
+  children: T;
+}
+
+export interface DecodedSchemaTreeCache<T> {
+  children: T;
+  isStale: boolean;
+}
+
+export function encodeSchemaTreeCache<T>(children: T, nowMs = Date.now()): SchemaTreeCacheEnvelope<T> {
+  return {
+    version: 2,
+    cachedAt: new Date(nowMs).toISOString(),
+    children,
+  };
+}
+
+export function decodeSchemaTreeCache<T>(payload: unknown, nowMs = Date.now(), ttlMs = SCHEMA_TREE_CACHE_TTL_MS): DecodedSchemaTreeCache<T> | null {
+  if (Array.isArray(payload)) {
+    return { children: payload as T, isStale: true };
+  }
+
+  if (!payload || typeof payload !== "object") return null;
+
+  const envelope = payload as Partial<SchemaTreeCacheEnvelope<unknown>>;
+  if (envelope.version !== 2 || !Array.isArray(envelope.children) || typeof envelope.cachedAt !== "string") {
+    return null;
+  }
+
+  const cachedAtMs = Date.parse(envelope.cachedAt);
+  if (!Number.isFinite(cachedAtMs)) return null;
+
+  return {
+    children: envelope.children as T,
+    isStale: nowMs - cachedAtMs >= ttlMs,
+  };
+}