fix(e2e): seed dev user in localStorage to prevent login redirect

E2E tests were failing because the dev login selector redirects to
/login when AUTH_DISABLED=true and no dev user is in localStorage.
Added a shared Playwright fixture that pre-seeds localStorage with
a default dev user before each test.

Also rebased onto latest main to resolve merge conflict in App.test.tsx.

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

apps/web/src/lib/devFetch.ts

@@ -5,6 +5,8 @@ const originalFetch = window.fetch;
 /**
  * Patches global fetch to include X-Dev-User-Id header on API requests
  * when a dev user is selected via the login selector.
+ *
+ * Intentionally mutates window.fetch — this is dev-only (AUTH_DISABLED=true).
  */
 export function installDevFetchInterceptor() {
   window.fetch = function (input: RequestInfo | URL, init?: RequestInit) {