06f2df4f89
Notify-and-fetch follow-ups: - PendingDeploymentPurgeActor: a central cluster singleton (not readiness-gated, best-effort) that sweeps expired PendingDeployment staging rows on CommunicationOptions.PendingDeploymentPurgeInterval (default 1h). Modeled on the kpi-history-recorder pattern: self-scheduling timer, per-tick DI scope -> IDeploymentManagerRepository, continue-on-error. Wired in AkkaHostedService.RegisterCentralActors (manager + proxy + drain); resolves the deferred TODO in DeploymentService. Correctness never depends on it (supersession bounds rows to <=1/instance; the fetch endpoint enforces the TTL), so it is deliberately absent from RequiredSingletonsHealthCheck. - SQL Server integration test for StagePendingIfAbsentAsync re-staging an instance's OWN DeploymentId over an expired row against the real UNIQUE index on DeploymentId — confirms EF orders DELETE before INSERT in one SaveChanges (SQLite's constraint timing differs from SQL Server's). Plus a same-instance supersession variant on real SQL Server. Tests: 2 TestKit actor tests + 2 SQL Server integration tests (both ran green against the infra MSSQL container); 235 Communication + 15 PendingDeployment tests pass; Host builds 0 warnings.