coreLoop now saves incremental checkpoints after each tool-call turn
and checks a cooperative stop signal at turn boundaries. SuspendedError
is handled in finishRun, executeParallel, and executeSingleTool.
Approval-interrupted checkpoints are persisted for both flat and
nested interruptions.
Introduce RunOption, WithCheckpointStore, RunWithOpts, ResumeWithOpts,
and RunStreamedWithOpts so callers can provide checkpoint storage.
Add StreamEventSuspended and OnRunRestore hook.
Signed-off-by: Aurélien Sibiril <81782+aureliensibiril@users.noreply.github.com>
