feat: add unit and integration tests for rental management domain

- Introduced RentPaymentCorrectionTest and RentPaymentTest to validate payment and refund logic.
- Added PhoneNumberTest to ensure proper normalization of phone numbers.
- Created TenantTest to verify attachment management and tenant referencing.
- Implemented ReplacementRentalApiJourneyIT for end-to-end testing of rental and payment workflows.
- Documented architectural decisions in ADR-0014, emphasizing strict DDD boundaries and transaction management.

frontend/e2e/app.spec.ts

@@ -179,12 +179,14 @@ test('keeps apartment add and edit workflows usable', async ({ page }) => {
 });
 
 test('keeps the secured API check and logout available', async ({ page }) => {
+  let logoutMethod = '';
   await mockUser(page, true);
   await mockEmptyApartmentList(page);
   await page.route('**/api/hello', async (route) => {
     await route.fulfill({ contentType: 'text/plain', body: 'Service disponible' });
   });
   await page.route('**/logout', async (route) => {
+    logoutMethod = route.request().method();
     await route.fulfill({ contentType: 'text/html', body: '<h1>Signed out</h1>' });
   });
 
@@ -194,7 +196,8 @@ test('keeps the secured API check and logout available', async ({ page }) => {
 
   await page.getByTestId('primary-navigation').getByRole('button', { name: 'Réglages' }).click();
   await page.getByTestId('session-settings').getByRole('button', { name: 'Déconnexion' }).click();
-  await expect(page).toHaveURL(/\/logout$/);
+  await expect.poll(() => logoutMethod).toBe('POST');
+  await expect(page).toHaveURL(/\/$/);
 });
 
 test('follows operating-system changes for the System theme', async ({ page }) => {