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/tasks.md

@@ -1,25 +0,0 @@
-## 1. Route Hover → Chart Highlight
-
-- [x] 1.1 Add invisible interactive overlay polyline on the route in PlannerMap for hover detection (avoids adding listeners to every ColoredRoute segment)
-- [x] 1.2 On polyline hover, find closest route coordinate index and compute cumulative distance
-- [x] 1.3 Pass `highlightChartDistance` up from PlannerMap to SessionView
-- [x] 1.4 Accept `highlightDistance` prop in ElevationChart, find closest point by distance, draw crosshair
-
-## 2. Chart Click → Map Pan
-
-- [x] 2.1 Add click handler to ElevationChart canvas — convert x-position to route coordinate
-- [x] 2.2 Call `onClickPosition([lat, lon])` callback to pan the map
-- [x] 2.3 Wire the callback through SessionView to call `map.panTo()` via the exposed map ref
-
-## 3. Chart Drag-Select → Map Zoom
-
-- [x] 3.1 Add mousedown/mousemove/mouseup handlers for drag selection on ElevationChart canvas
-- [x] 3.2 Draw semi-transparent overlay rectangle during drag
-- [x] 3.3 On mouseup, compute bounding box of route coordinates in the selected distance range
-- [x] 3.4 Call `onDragSelect(bounds)` callback to zoom the map via `map.fitBounds()`
-- [x] 3.5 Show "Reset zoom" button after drag-zoom, clicking it returns to full route bounds
-
-## 4. Testing
-
-- [x] 4.1 E2E test: hover chart → map dot appears (existing, verify still works)
-- [x] 4.2 E2E test: click chart → map pans (verify map center changes)