test: centralize demo IDs and site_domain mock in env.ts

- Added testing_site_id, testing_site_domain_id, testing_fqdn, testing_person_id
- Created mock_site_domain object matching +layout.ts expectations
- Updated minimal_v3_mocks.ts to use mock_site_domain
- Fixes 'Domain Not Registered' overlay in Playwright tests
- All test IDs now documented with comments from tests/README.md

tests/_helpers/env.ts

@@ -4,14 +4,46 @@
  */
 export const test_base_url = 'http://demo.localhost:5173';
 export const dev_api_base = 'https://dev-api.oneskyit.com';
-export const testing_account_id = '_XY7DXtc9MY';
-export const testing_event_id = 'pjrcghqwert';
+
+// Core test/demo IDs (from tests/README.md)
+export const testing_account_id = '_XY7DXtc9MY';  // (1) "One Sky IT Demo"
+export const testing_site_id = '92vkYC4fVEl';     // (12) "One Sky IT Demo"
+export const testing_site_domain_id = '_6jcTbnJk-o';  // (12) "demo.localhost:5173"
+export const testing_fqdn = 'demo.localhost:5173';
+
+// Events test/demo IDs
+export const testing_event_id = 'pjrcghqwert';  // (1) "Demo One Sky IT Conference"
+export const testing_person_id = 'QWODAPCNLQU';  // (49) "Osiris Idem"
+
+/**
+ * Mock site_domain object for Playwright tests.
+ * Matches the structure expected by +layout.ts lookup_site_domain_v3()
+ */
+export const mock_site_domain = {
+  id: testing_site_domain_id,
+  site_id: testing_site_id,
+  site_domain_id: testing_site_domain_id,
+  account_id: testing_account_id,
+  account_id_random: testing_account_id,
+  account_code: 'OSIT_DEMO',
+  account_name: 'One Sky IT Demo',
+  fqdn: testing_fqdn,
+  enable: '1',
+  cfg_json: {},
+  style_href: '',
+  header_image_path: ''
+};
 
 export const TEST_ENV = {
   test_base_url,
   dev_api_base,
   testing_account_id,
-  testing_event_id
+  testing_site_id,
+  testing_site_domain_id,
+  testing_fqdn,
+  testing_event_id,
+  testing_person_id,
+  mock_site_domain
 };
 
 export default TEST_ENV;