Awaited deadline oracles get the runner token; sync-over-async tests made async;
nullable child models asserted via ShouldNotBeNull() return values; obsolete SDK
ctors replaced with the telemetry overloads; dead locals/fixture and the redundant
DI PackageReference removed. No suppressions.
Claude-Session: https://claude.ai/code/session_01GT67AEHd2Acv1YPwGfXEoV
R08 1.4: raw and modified history reads share HistoryReadPaging. A read stopped by
the caller's cap releases the server continuation point. The raw path also passed
releaseContinuationPoints = (cp != null), which released page two instead of reading
it, so every raw read was silently truncated to its first server page.
R08 1.5: DefaultSubscriptionAdapter removes its Subscription from the SDK Session
on delete/dispose (and a failed CreateAsync removes it too), so re-targeted alarm
subscriptions no longer accumulate in Session.Subscriptions.
Refs #747
Claude-Session: https://claude.ai/code/session_01Ub9hGmYLQvn9XETzw7CMsT
Joseph Doherty