#4466 Workflow-scoped data get reports the behavior id as modelName once the behavior definition is deleted

Description

swamp data get --workflow --run (and serve's workflow-scoped data.get) returns the behavior's id in the top-level modelName field when the behavior that wrote the item has been deleted. The item's tags.modelName still holds the real behavior name.

Found while triaging swamp-club#4464.

Cause

WorkflowDataService.resolveModelName in src/domain/data/workflow_data_service.ts looks the definition up by id and falls back to the id when it is not found, instead of the name recorded on the data.

Expected

modelName is the behavior name the data recorded (tags.modelName), whether or not the definition still exists.

Steps to reproduce

1. Run a workflow whose step uses a per-run inline behavior, then delete that behavior's auto-definition.
2. swamp data get --workflow log --run --json
3. The top-level modelName is the behavior's UUID; tags.modelName is the name.