Prototype unified state and federal bill tracker

[PavelMakarchuk]

Summary

• reframe the app as a tax and transfer bill tracker while keeping state-first navigation
• add a first-class federal route and federal workspace alongside the existing state flow
• separate legislative session scope from calendar activity year with reusable filter UI and state/federal panel support

Details

• add jurisdiction-aware routing, search, and breadcrumbs
• add a FederalPanel and shared session/year filter components
• extend the data layer with federal bill/research helpers and carry date/session metadata into UI models
• document the intended architecture in docs/GENERAL_BILL_TRACKER_ARCHITECTURE.md

Testing

• npm run build

Notes

• unrelated OpenStates script changes remain uncommitted in the worktree and are not part of this PR