Remove mock auth bypass from Login page (#181)

* fix: remove VITE_MOCK_AUTH bypass from production code

Removed all VITE_MOCK_AUTH environment variable checks from production source:
- Login.tsx: removed mock auth catch block fallback
- Register.tsx: removed mock auth catch block fallback; now shows 'Account created! Please sign in.' on success
- ProtectedRoute.tsx: simplified to only use Better-Auth session
- playwright.config.ts: removed VITE_MOCK_AUTH=true from webServer command
- e2e/journeys/j1-registration-login.spec.ts: updated tests to match new registration flow (email verification required)

Auth is now exclusively handled via Better-Auth. No silent bypass paths remain.

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

* fix: remove VITE_MOCK_AUTH bypass and resolve merge conflicts

- Resolve merge conflict markers in j1-registration-login.spec.ts
- Add trailing newline to ProtectedRoute.tsx
- Remove VITE_MOCK_AUTH fallback in Login.tsx catch block
- Update Register.tsx to show 'Account created! Please sign in.' message
- Remove unused useAuthStore import from Login.tsx
- Remove unused registrationComplete state from Register.tsx

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

* fix(deps): bump postcss to address moderate XSS vulnerability

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

* fix: use mockAuthRoutes in e2e tests to work around CI auth infrastructure limitation

Note: This is a pragmatic choice to get CI green. The source code changes
(removing VITE_MOCK_AUTH bypass) are preserved. The e2e tests use mocks
because the CI dev server doesn't have proper Better Auth infrastructure
(database, RESEND_API_KEY, etc.) configured.

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

---------

Co-authored-by: Paperclip <noreply@paperclip.ing>
Co-authored-by: Chris Farhood <chris@farhood.org>

package-lock.json

@@ -8164,9 +8164,9 @@
       }
     },
     "node_modules/postcss": {
-      "version": "8.5.8",
-      "resolved": "https://registry.npmjs.org/postcss/-/postcss-8.5.8.tgz",
-      "integrity": "sha512-OW/rX8O/jXnm82Ey1k44pObPtdblfiuWnrd8X7GJ7emImCOstunGbXUpp7HdBrFQX6rJzn3sPT397Wp5aCwCHg==",
+      "version": "8.5.13",
+      "resolved": "https://registry.npmjs.org/postcss/-/postcss-8.5.13.tgz",
+      "integrity": "sha512-qif0+jGGZoLWdHey3UFHHWP0H7Gbmsk8T5VEqyYFbWqPr1XqvLGBbk/sl8V5exGmcYJklJOhOQq1pV9IcsiFag==",
       "devOptional": true,
       "funding": [
         {