fix(native): fix widget image management and add tests

- Fix `copyBundledAsset` to accept a URI instead of a named bundle asset, resolving via `resolveAssetURL` with support for remote downloads
- Read app group identifier from Info.plist (`ExpoWidgetsAppGroupIdentifier`) instead of a hardcoded string
- Add `pruneWidgetImages(maxAgeSeconds)` to age-based cache cleanup, skipping the widget icon file
- Add `normalizedFileName` helper to sanitize cache keys and a `log` helper with consistent prefix
- Extract `getWidgetIconAsset()` into `widget-assets.ts` so the asset require is testable in isolation
- Add Vitest config for the native app and unit tests covering widget data-fetch, image download, and prune logic

apps/native/vitest.config.ts

@@ -0,0 +1,15 @@
+import path from "node:path";
+
+import { defineProject } from "vitest/config";
+
+export default defineProject({
+  resolve: {
+    alias: {
+      "@": path.resolve(__dirname, "src"),
+    },
+  },
+  test: {
+    include: ["src/**/*.test.ts"],
+    environment: "node",
+  },
+});