Fix waypoint drag creating unwanted split points

The ghost marker (route split indicator) was interfering with waypoint
dragging because it sat above waypoints (zIndexOffset 1000) and stayed
active during drag operations.

Adopt brouter-web's suspension pattern:
- Suspend route interaction on waypoint mouseover (not just dragstart),
  unsuspend on mouseout — ghost marker hides before any click/drag
- Lower ghost marker zIndexOffset to -100 so waypoints always receive
  clicks first
- Keep drag guards as a safety net

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

apps/planner/app/components/PlannerMap.tsx

@@ -179,6 +179,8 @@ export function PlannerMap({ yjs, onRouteRequest, highlightPosition }: PlannerMa
   const [noGoDrawing, setNoGoDrawing] = useState(false);
   const toggleNoGoDraw = useCallback(() => setNoGoDrawing((v) => !v), []);
   const suppressMapClickRef = useRef(false);
+  const routeInteractionSuspendedRef = useRef(false);
+  const waypointDraggingRef = useRef(false);
 
   // Sync waypoints from Yjs
   useEffect(() => {
@@ -324,7 +326,21 @@ export function PlannerMap({ yjs, onRouteRequest, highlightPosition }: PlannerMa
           draggable
           icon={waypointIcon(i)}
           eventHandlers={{
+            mouseover: () => {
+              routeInteractionSuspendedRef.current = true;
+            },
+            mouseout: () => {
+              if (!waypointDraggingRef.current) {
+                routeInteractionSuspendedRef.current = false;
+              }
+            },
+            dragstart: () => {
+              waypointDraggingRef.current = true;
+              routeInteractionSuspendedRef.current = true;
+            },
             dragend: (e) => {
+              waypointDraggingRef.current = false;
+              routeInteractionSuspendedRef.current = false;
               const { lat, lng } = e.target.getLatLng();
               moveWaypoint(i, lat, lng);
             },
@@ -347,6 +363,7 @@ export function PlannerMap({ yjs, onRouteRequest, highlightPosition }: PlannerMa
             coordinates={routeCoordinates}
             segmentBoundaries={segmentBoundaries}
             onInsertWaypoint={handleRouteInsert}
+            suspendedRef={routeInteractionSuspendedRef}
             disabled={noGoDrawing}
           />
         </>