feat(session-limits): LS3 — port Scheduler + adapter TokioScheduler

Introduit l'abstraction de planification pour la reprise différée à la
levée d'une limite de session :
- domaine : trait Scheduler + enum ScheduledTask (ports.rs), ScheduleId
  via typed_id! (ids.rs), re-exports (lib.rs).
- infra : TokioScheduler (scheduler/mod.rs, nouveau) + pub mod scheduler
  et re-export (lib.rs).

Tests QA inline (#[cfg(test)]) : 7 tests scheduler (3× sans flaky).
`cargo test -p infrastructure` = 195 passed / 0 failed ; domaine + infra
builds 0 warning ; LS1/LS2 toujours verts.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

crates/infrastructure/src/lib.rs

@@ -30,6 +30,7 @@ pub mod pty;
 pub mod remote;
 pub mod runtime;
 pub mod sandbox;
+pub mod scheduler;
 pub mod session;
 pub mod store;
 
@@ -59,6 +60,7 @@ pub use runtime::CliAgentRuntime;
 #[cfg(target_os = "linux")]
 pub use sandbox::LandlockSandbox;
 pub use sandbox::{default_enforcer, NoopSandbox};
+pub use scheduler::TokioScheduler;
 pub use session::{ClaudeSdkSession, CodexExecSession, FakeCli, StructuredSessionFactory};
 #[cfg(feature = "vector-onnx")]
 pub use store::OnnxEmbedder;