Phase 2a: plumb config.coverage.bbox through EnvironmentalStore to adapter
constructors (mirroring region_anchors) and wire the four straightforward
native adapters to derive their scope from it — usgs_quake/roads511 bbox,
wzdx states+bbox, avalanche center_ids — via resolve_adapter_coverage().
Coverage bbox (when set) governs; the adapter's own config field is the
fallback when unset. Central-fed adapters are unaffected (never native-
constructed). fires/firms/hydro/traffic/satpass/ducting/nws follow.
Co-authored-by: Matt Johnson <mj@k7zvx.com>
Co-authored-by: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
