fix(e2e): correct Better Auth mock route patterns

- Changed sign-up route from /auth/register to /auth/sign-up/email
- Changed session route from /auth/session to /auth/get-session

Better Auth hits /auth/sign-up/email for registration and /auth/get-session for session checks.

Co-Authored-By: Paperclip <noreply@paperclip.ing>

e2e/fixtures.ts

@@ -15,7 +15,7 @@ const MOCK_USER_ID = "mock_user_123";
 const MOCK_SESSION_ID = "mock_session_456";
 
 function mockAuthRoutes(page: Page, authenticated = false) {
-  page.route(/\/auth\/register/, async (route) => {
+  page.route(/\/auth\/sign-up\/email/, async (route) => {
     await route.fulfill({
       status: 200,
       contentType: "application/json",
@@ -67,7 +67,7 @@ function mockAuthRoutes(page: Page, authenticated = false) {
     });
   });
 
-  page.route(/\/auth\/session/, async (route) => {
+  page.route(/\/auth\/get-session/, async (route) => {
     if (authenticated) {
       await route.fulfill({
         status: 200,