* op-program: Support agreed prestate hint in host

* op-program: Fix transition state serialization in test

* op-program: Fix prefetcher_test.go

* op-program: Prevent specifying both --l2.outputroot and --l2.agreed-prestate flags

Check config is consistent

* op-program: Return safe or local safe head from derivation

Avoids relying on the safe label which won't be updated on interop chains.

* op-program: Only stop derivation if local safe reaches the target block.

* op-program: Fix safe head trace extension

* op-program: Remove unused field.