In scope:
- Consolidate `WorkflowService.getMany()`.
- Support non-entity field `ownedBy` for `select`.
- Support `tags` for `filter`.
- Move `addOwnerId` to `OwnershipService`.
- Remove unneeded check for `filter.id`.
- Simplify DTO validation for `filter` and `select`.
- Expand tests for `GET /workflows`.
Workflow list query DTOs:
```
filter → name, active, tags
select → id, name, active, tags, createdAt, updatedAt, versionId, ownedBy
```
Out of scope:
- Migrate `shared_workflow.roleId` and `shared_credential.roleId` to
string IDs.
- Refactor `WorkflowHelpers.getSharedWorkflowIds()`.