feat(tours): route paddle tours on the water, shaping points and auto-loaded regions

Paddle tours are planned on the water by TREK's own router: a water network
per paddle region, built from the same Geofabrik extract as the obstacles and
searched in a worker thread of the server (no sidecar). Rivers, canals and
lakes (direct or along the shore), portages round weirs, locks by policy,
whitewater by boat, gaps marked. Found portages and locks become points of
their own; an unplannable leg says why and offers a way out.

- Shaping points: a click on the line sets a point that steers the route
  without being a stop (hikes and paddle tours); recompute a single leg.
- Lake style direct/shore, suggested from the wind forecast.
- Regions load by themselves where a paddler plans (admin setting: automatic,
  on request, off; size cap and a daily count), with requests for the admins,
  a notification, and the load followed on the leg.
- Portage from the last point, portages follow footways via the walking
  router (or stay straight), "put in here" on slipways and put-ins.
- MCP plan_paddle_route with the REST route's rules.

client/src/components/Map/MapView.tsx

@@ -8,6 +8,7 @@ import { CLUSTER_OPTIONS, createClusterIcon, revealInCluster, type ClusterGroupL
 import RoadtripViaMarkers from './RoadtripViaMarkers'
 import PlannerWaypointMarker from './PlannerWaypointMarker'
 import HazardLayers from './HazardLayers'
+import { RouteHitBand } from './RouteHitBand'
 import { formatViaDwell } from './routeViaDwell'
 import { ALT_CASING, ALT_LABEL_TEXT } from '../Roadtrip/alternativeColors'
 import { serviceMarkerHtml, serviceMarkerOuter } from '../Roadtrip/serviceMarker'
@@ -1158,8 +1159,7 @@ export const MapView = memo(function MapView({
       </MarkerClusterGroup>
 
       {/* Apple-Maps style: darker-blue casing under a bright-blue core, rounded.
-          The casing carries the click when the route can be reshaped: it is the wider of
-          the two, so it is the one a pointer actually lands on. */}
+          When the route can be reshaped an invisible band wider than both takes the click. */}
       {route && route.length > 0 && route.flatMap((seg, i) => seg.length < 2 ? [] : routeWalking?.[i] ? [
         // Walked, so dashed and without the casing: the drive is the solid line (#2532).
         <Polyline
@@ -1173,15 +1173,7 @@ export const MapView = memo(function MapView({
           key={`${i}-casing`}
           positions={seg}
           pathOptions={{ color: routeColors?.[i]?.casing ?? '#0a5cc2', weight: 8, opacity: 1, lineCap: 'round', lineJoin: 'round' }}
-          interactive={!!onRouteClick}
-          eventHandlers={onRouteClick ? {
-            click: (e: { latlng: { lat: number; lng: number }; originalEvent: MouseEvent }) => {
-              // Stops the map's own click, which would otherwise open the add-place menu
-              // underneath the new via.
-              e.originalEvent.stopPropagation()
-              onRouteClick(e.latlng.lat, e.latlng.lng)
-            },
-          } : undefined}
+          interactive={false}
         />,
         <Polyline
           key={`${i}-core`}
@@ -1189,6 +1181,7 @@ export const MapView = memo(function MapView({
           pathOptions={{ color: routeColors?.[i]?.line ?? '#0a84ff', weight: 5, opacity: 1, lineCap: 'round', lineJoin: 'round' }}
           interactive={false}
         />,
+        ...(onRouteClick ? [<RouteHitBand key={`${i}-hit`} positions={seg} onRouteClick={onRouteClick} />] : []),
       ])}
 
       {/* The last bit to a place the road does not reach.