feat: ask for vessels by area

The vessel source accepts an optional area and sends it as lat, lon and
radius_km. The vessel layer asks for the area the camera shows (centered
on the middle of the screen, sized by camera height), or every vessel
from high enough up, and asks again when the view moves or zooms by a
quarter of that radius. vessels_in_area names its area too. Servers that
hold every vessel may ignore the area; callers still keep only what is
inside it.

src/layers/vessels/lifecycle.js

@@ -196,10 +196,18 @@ export function createLifecycle({
         state.records.byMmsi.has(pickedId),
       );
       restoreSpriteOrderOnEnable('ais', activeViewer);
+      // Vessels are asked for by view, so ask again when the view moves away.
+      removeViewListener();
+      const moveEnd = activeViewer?.camera?.moveEnd;
+      if (typeof moveEnd?.addEventListener === 'function')
+        state.feed.removeViewListener = moveEnd.addEventListener(() => {
+          components.ingestion.refreshIfMoved(activeViewer);
+        });
       return components.ingestion.loadLivePositions(activeViewer);
     },
 
     disable() {
+      removeViewListener();
       state.feed.enabled = false;
       invalidateAisSession();
       releaseContinuousRender('ais-vessels');
@@ -218,6 +226,7 @@ export function createLifecycle({
     },
 
     destroy(viewer) {
+      removeViewListener();
       const activeViewer = viewer || state.viewer;
       invalidateAisSession();
       releaseContinuousRender('ais-vessels'); // direct-destroy path (perf wave 2 fix)
@@ -241,6 +250,12 @@ export function createLifecycle({
     },
   };
 
+  function removeViewListener() {
+    const remove = state.feed.removeViewListener;
+    state.feed.removeViewListener = null;
+    if (typeof remove === 'function') remove();
+  }
+
   return {
     clearFirstConnectTimer,
     invalidateAisSession,