fix(terrain): keep a batch's warm points when its own fetches evict them

A warm entry could be evicted by the same call's later fetches and then
reported unresolved. The call now remembers warm hits as it does fetched ones.
Moves the batch LRU test beside the existing cache tests and folds the docs
note into the section's eviction paragraph.

src/services/terrainHeights.test.mjs

@@ -114,6 +114,47 @@ test('a batch larger than the cache bound still reports every point it resolved'
   assert.equal(warm.length, 4);
 });
 
+test('warm batch consumers retain their terrain cells ahead of unused cells', async () => {
+  let calls = 0;
+  const terrain = createTerrainHeights({
+    maxCacheEntries: 2,
+    source: {
+      async getHeights(points) {
+        calls++;
+        return points.map((p) => ({ ellipsoid: 100 + p.lon }));
+      },
+    },
+  });
+  const p = (lon) => ({ lat: 0, lon });
+  await terrain.resolveEllipsoidalGround([p(1)]);
+  await terrain.resolveEllipsoidalGround([p(2)]);
+  await terrain.resolveEllipsoidalGround([p(1)]);
+  assert.equal(calls, 2);
+  await terrain.resolveEllipsoidalGround([p(3)]);
+  assert.equal(terrain.cachedEllipsoidalGround(0, 1), 101);
+  assert.equal(terrain.cachedEllipsoidalGround(0, 2), null);
+  assert.equal(calls, 3);
+});
+
+test('a batch still reports its warm points after its own fetches evict them', async () => {
+  const terrain = createTerrainHeights({
+    source: stubSource(),
+    maxCacheEntries: 2,
+  });
+  await terrain.resolveEllipsoidalGround([pointAt(0)]);
+
+  const results = await terrain.resolveEllipsoidalGround([
+    pointAt(0),
+    pointAt(1),
+    pointAt(2),
+  ]);
+
+  results.forEach((result, i) => {
+    assert.equal(result.source, 'reearth', `point ${i} reported resolved`);
+    assert.equal(result.ellipsoid, heightAt(lonAt(i)));
+  });
+});
+
 test('an out-of-range cache bound falls back to the default instead of disabling the cache', async () => {
   for (const maxCacheEntries of [0, -1, Number.NaN, undefined]) {
     const terrain = createTerrainHeights({