Replace interface{} fields in runtime.PendingExecution with typed handles:
- Driver: *engine.RecoveryDriver (was interface{})
- Plan: *engine.RecoveryPlan (was interface{})
- CatchUpIO: engine.CatchUpIO (was interface{})
- RebuildIO: engine.RebuildIO (was interface{})
block_recovery.go:
- ExecutePendingCatchUp/Rebuild: direct field access (pe.Driver, pe.Plan)
instead of type assertions (pe.Driver.(*engine.RecoveryDriver))
- CancelFunc: pe.Driver.CancelPlan(pe.Plan, reason) — no casts
- 6 type assertions removed from production path
Test files: remove Plan type assertions — fields are typed end-to-end.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>