feat(app-expo): env variants, local iOS prebuild, and About diagnostics

Align staging/production builds with APP_VARIANT bundle IDs, allow staging HTTP on iOS, add ios-prebuild scripts for TestFlight, and show connected API URL on About for non-production builds.

Co-authored-by: Cursor <cursoragent@cursor.com>

app-expo/tests/core/config.test.ts

@@ -0,0 +1,23 @@
+import {
+  appVariant,
+  config,
+  shouldShowAboutBackendUrl,
+  type AppVariant,
+} from '@/core/config';
+
+describe('shouldShowAboutBackendUrl', () => {
+  it('shows backend URL for development and staging', () => {
+    expect(shouldShowAboutBackendUrl('development')).toBe(true);
+    expect(shouldShowAboutBackendUrl('staging')).toBe(true);
+  });
+
+  it('hides backend URL for production', () => {
+    expect(shouldShowAboutBackendUrl('production')).toBe(false);
+  });
+
+  it('matches config.showAboutBackendUrl for current build', () => {
+    expect(config.showAboutBackendUrl).toBe(
+      shouldShowAboutBackendUrl(appVariant as AppVariant),
+    );
+  });
+});