Replaces the hand-rolled per-adapter region heuristics (which leaked LA/OR
broadcasts) with Central's proven mechanism: bounding-box(es) + Shapely
full-geometry intersection. Ports MonitoringArea/build_geom_json/
classify_geom_areas from the central repo; adds config.coverage.areas
(multi-box, set-union) and a CoverageFilter that gates every event on
geometry-in-any-area before broadcast. Adapter geometry enrichment (NWS
polygons, fail-closed) follows in the next phase.
Co-authored-by: Matt Johnson <mj@k7zvx.com>
Co-authored-by: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
