- Add dropdown state for date filters (selected_initiated, selected_last_seen)
- Add date_filter_id computed property combining the two selections
- Add load_pathway_data() method to query pathway_nodes table
- Add recalculate_parent_totals() for filtered hierarchies
- Update all filter handlers to call load_pathway_data()
- Update KPI calculations from root node data
Phase 3 Reflex integration: Task 3.1 complete