Add option to auto-create baseline from reform's population

Context

User feedback from Greg Miller (Land Economics) while using the report creation flow.

Problem

When creating a report, users must manually create both a baseline and reform simulation. Greg suggested a "baseline" checkbox that automatically creates a baseline using current law for the same households/geography as the reform.

Currently there is a DefaultBaselineOption that creates a nationwide current-law baseline, but it doesn't match the reform's specific population — it always uses national scope.

Suggested behavior

When setting up simulation 2 (reform), offer an option like:

"Auto-create baseline: Run current law on the same households as this reform"

This would:

1. Take the reform's population (household or geography selection)
2. Create a baseline simulation with current law + that same population
3. Skip the manual baseline creation step entirely

UX questions to discuss

• Should this be a checkbox on the reform setup, or a new option on the baseline selection screen?
• Should it be the default behavior (with opt-out) or an explicit opt-in?
• How does this interact with the existing DefaultBaselineOption (nationwide current law)?

Files

• app/src/pathways/report/views/ReportSimulationSelectionView.tsx
• app/src/pathways/report/components/DefaultBaselineOption.tsx
• app/src/pathways/report/ReportPathwayWrapper.tsx

Start with app/src/pathways/report/views/ReportSimulationSelectionView.tsx, then read DefaultBaselineOption.tsx and ReportPathwayWrapper.tsx to understand the existing baseline flow. Decide where the opt-in behavior belongs and how it interacts with the nationwide option. Done means a reform can create a current-law baseline using its same household or geography population without manual baseline creation.