Archive elevation-map-interaction, sync spec to main

Synced new spec (chart ↔ map interaction, mobile touch, iOS safe area,
responsive header) to openspec/specs/elevation-map-interaction/.

All 4 artifacts complete. All 14 tasks complete.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

openspec/changes/elevation-map-interaction/proposal.md

@@ -1,21 +0,0 @@
-## Why
-
-The elevation chart and map currently have one-directional interaction: hovering the chart shows a red dot on the map. But hovering the route on the map doesn't highlight the chart, clicking the chart doesn't pan the map, and there's no way to zoom into a section of the route from the chart. This makes it hard to correlate what you see on the map with what you see in the elevation profile.
-
-## What Changes
-
-- **Route hover → chart marker**: Hovering over the route polyline on the map shows the corresponding position on the elevation chart with a crosshair
-- **Chart click → map pan**: Clicking on the elevation chart pans the map to center on that point along the route
-- **Chart drag → map zoom**: Dragging/selecting a range on the elevation chart zooms the map to fit that section of the route
-
-## Capabilities
-
-### Modified Capabilities
-- `route-coloring`: Elevation chart gains bidirectional interaction with the map
-- `map-display`: Route polyline hover reports position back to the chart
-
-## Impact
-
-- `ElevationChart.tsx`: Add click handler (pan map), drag-select handler (zoom map), accept highlighted index from map hover
-- `PlannerMap.tsx` / `ColoredRoute.tsx`: Route polyline hover finds closest point and reports index/position back to SessionView
-- `SessionView.tsx`: Wire bidirectional state between chart and map