ScenarioExplorer

Explores contract state space by applying actions at each step.

ScenarioExplorer performs bounded exploration of contract interactions. At each depth it:

1. Gets a snapshot reader
2. Calls the step function which performs one interaction using normal Scenario operations
3. Actions (Scenario.submit, Scenario.sleep) are automatically logged
4. On successful step, recurses to next depth
5. On check failure, captures violation with the full action path
6. On other errors, propagates

The step function can use Scenario.choices/Scenario.fromCollection for branching, Scenario.submit for transactions, Scenario.sleep for time advancement, and Scenario.check for invariant verification.