Stabilise XCUITest app lifecycle and first exercise sheet readiness on CI #83

Two CI UI coverage attempts on #82 at unchanged commit c23c03b each passed 26 of 27 tests, with different failures. This core suggestion slice changes no app or UI test files, and the app does not call its new API.

The initial attempt failed ProfileJourneyUITests.testAchievementsSectionVisible in setUpWithError at app.launch(), because XCUITest could not terminate the previous BetterFit process. The test did not reach its assertions.

• Initial job log
• Initial result bundle

The isolated rerun passed the profile test but failed AdjustSetsUITests.testExerciseDetailShowsSetControls at line 86. After tapping the Focus exercise static text, Sets did not appear within three seconds. The retained app hierarchy still shows Plan and the Lat pulldown button, rather than the exercise detail sheet. The same set-controls test passed in the initial attempt.

• Rerun log
• Rerun result bundle

Investigate app lifecycle cleanup and first-test exercise sheet readiness on a fresh CI simulator. Preserve failures and verify the complete 27-test suite without suppressing assertions or adding blind retries. These observations do not establish a shared root cause with the mobilewright failures tracked in #62.