Create a single-file interactive maproom benchmark with layered cartography, filters, annotations, place-driven storytelling, and no external map tiles.

## Route brief followed

- Build a self-contained `/maproom/` HTML artifact, with no external map tiles or remote assets.
- Present an authored layered atlas and cartographic explorer rather than a generic dashboard.
- Include multiple overlay modes, readable legends, filters, annotation callouts, location detail views, and a guided route.
- Support keyboard, mouse, and touch navigation with zoom and pan.
- Persist visited locations and overlay preferences locally.

## Layer set

- Base bathymetric chart with graticule, coastline forms, depth bands, reefs, and harbour geometry.
- Risk layer showing tide gates, fog banks, collision corridors, and restricted waters.
- Infrastructure layer showing relay towers, ferry lanes, research buoys, and repair depots.
- Ecology layer showing kelp reserves, bird nesting cliffs, seal haul-outs, and nursery waters.
- Historical layer showing old trade routes, wreck sites, quarantine anchorages, and vanished settlements.

## Navigation model

- Drag or touch-drag to pan.
- Mouse wheel, pinch, plus/minus buttons, and keyboard shortcuts to zoom.
- Arrow keys pan the chart; number keys select overlay modes; `G` starts the guided tour; `R` resets the view.
- Selecting a place opens a detailed atlas card and marks it visited.

## Visual direction

- Night-maproom interface with brass, cyan, amber, and sea-glass accents.
- SVG cartography drawn in-browser with crisp labels, contour-like depth bands, and annotated routes.
- Dense enough to reward exploration, but legible on mobile.