Fix per-test isolation flakiness: relaunch instead of UI logout; 4 workers

The first full 8-worker run surfaced 52 failures, 28 of them "Failed to log out"
(UITestHelpers:86) — forcing a profile-navigation logout between every test (each
test = new account) is fragile, and 8 parallel simulator clones thrashed the
machine (the remaining failures were UI timeouts under that load).

- AuthenticatedUITestCase: relaunchBetweenTests = true. A fresh app launch with
  --reset-state lands on the login screen, so each test logs in as its own account
  with NO UI logout between tests. Removed the ensureLoggedOut call.
- run_ui_tests.sh: default workers 8 -> 4 (reliable on a Mac mini; each test now
  relaunches + creates an account, so the bottleneck is CPU/simulator).

Verified: ContractorUITests (was ~15 logout failures) now passes at 4 workers,
0 leaked accounts.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

iosApp/HoneyDueUITests/Framework/AuthenticatedUITestCase.swift

@@ -17,6 +17,12 @@ class AuthenticatedUITestCase: BaseUITestCase {
     /// (sets OnboardingState.hasCompletedOnboarding) so login lands on main tabs.
     override var completeOnboarding: Bool { true }
 
+    /// Per-test isolation relaunches the app fresh for every test. With
+    /// --reset-state this lands on the login screen, so each test logs in as its
+    /// own fresh account WITHOUT a fragile UI logout between tests (the old
+    /// logout-via-profile path was the #1 source of flakes under load).
+    override var relaunchBetweenTests: Bool { true }
+
     /// Credentials for the Kratos APP identity used to seed data over the API.
     ///
     /// ⚠️ TWO DIFFERENT "admin@honeydue.com" EXIST — do NOT "fix" Test1234 to password123:
@@ -116,11 +122,10 @@ class AuthenticatedUITestCase: BaseUITestCase {
         try super.setUpWithError()
 
         if usesFreshAccount {
-            // Per-test isolation: every test logs in as its OWN fresh, pre-verified
-            // account, seeds under its token, and deletes it in teardown. The app
-            // may be reused from a previous test (still logged in as that test's
-            // account), so always log out first.
-            UITestHelpers.ensureLoggedOut(app: app)
+            // Per-test isolation: relaunchBetweenTests gives every test a fresh
+            // app launch that lands on the login screen (--reset-state), so we
+            // log in as a brand-new pre-verified account, seed under its token,
+            // and delete it in teardown. No UI logout between tests.
             let acct = TestAccount.create(domain: accountDomain)
             account = acct
             session = acct.session