Add a dedicated Deep Research view with postal-area preview overlays, batch execution, and bundled map results.
Also add postal dataset import tooling and fix local API networking and research insert issues needed to support the new workflow.
Replace Supabase auth and search runtime with a local Fastify API, PostgreSQL/PostGIS schema, and local session handling. Scaffold the worker and deep-research foundations while keeping the existing research, dashboard, and map flows running on the new backend.