Stabilize cold simulator preparation in CI

[heoblitz]

Summary

Cold hosted runners can time out during simulator discovery or the first app launch before connection assertions start. Pin Xcode 26.6 and the iPhone 17 Pro / iOS 26.2 baseline; include discovery, pre-boot via simctl bootstatus -b, and installation in a shared 660-second preparation budget. Allow 300 seconds for the first app launch.

Run E2E serially with -retry-tests-on-failure -test-iterations 2, allowing at most one retry. Swift Testing may repeat other tests in the same plan. Keep the 20-minute connection-test limit and allow 45 minutes for the CI job to cover both attempts and diagnostics. Preserve raw output and result bundles for every run, including failures followed by a successful retry. A repeated failure still fails the job.

Changes are limited to CI, E2E fixtures/tests, the E2E runner script and verification documentation. Connection, once/stream, disconnect and reconnect assertions remain intact.

Validation

• script/test-e2e build-mac: passed.
• Focused simulator selection, command deadline and host startup tests with retry flags: 8 passed.
• Verified the E2E shell script preserves a failing xcodebuild exit status through tee and captures raw logs.
• bash -n script/test-e2e and git diff --check: passed.
• Three consecutive complete hosted Check workflow passes on final commit 81acd100144e43d216d03852ef452c66eccd6585: attempt 1, attempt 2, attempt 3.
• Each attempt passed all five jobs, including all 9 E2E tests without needing a retry. E2E test durations were 452, 231 and 302 seconds.
• All three hosted runs confirmed the retry flags were active and successfully uploaded the E2E logs/result artifact. Recovery from an actual test failure was not exercised by these passing runs.