## Summary
- Extract `findParentSteps` utility that recognizes IF-ELSE steps as
parents of their branch children (via
`settings.input.branches[].nextStepIds`), used in all parent detection
sites (`shouldSkipStepExecution`, `shouldExecuteStep`,
`shouldFailSafely`, and their iterator variants)
- Centralize next-step resolution in `getNextStepIdsToExecute` via
extracted `getNextStepIdsForIterator` and `getNextStepIdsForIfElse`
utils — Iterator now properly returns loop children as
`nextStepIdsToSkip`/`nextStepIdsToFailSafely` when skipped
- Refactor `skipAndFailSafelyStepsThenContinue` to delegate to
`getNextStepIdsToExecute` instead of duplicating type-specific
propagation logic
Fixes#20934
## Test plan
- [x] New unit tests for `findParentSteps` (7 tests covering IF-ELSE
branch parent detection)
- [x] New IF-ELSE-specific tests added to `shouldSkipStepExecution`,
`shouldExecuteStep`, `shouldFailSafely` test suites
- [x] Updated Iterator skip/fail-safely tests in
`workflow-executor.workspace-service.spec.ts`
- [x] All 300 workflow executor tests pass
- [x] `lint:ci` passes
