fix(render): release the atmosphere probe's WebGL context

Lose the throwaway WebGL2 probe context right after the link probe instead
of leaving it for GC; browsers (Safari especially) cap live contexts. Note
that affected devices also lose globe-basemap fog, credit the changelog
entry and move it to the top.

Co-Authored-By: Claude Opus 5.5 (1M context) <[email protected]>

src/app/atmosphereCompat.js

@@ -154,7 +154,19 @@ export function shouldDisableModelAtmosphere({
 } = {}) {
   const gl = createProbeContext();
   if (gl) {
-    if (probeOutParamVaryingLinkFailure(gl)) return true;
+    let linkFails;
+    try {
+      linkFails = probeOutParamVaryingLinkFailure(gl);
+    } finally {
+      // Browsers cap live WebGL contexts (Safari especially); release the
+      // throwaway probe context now rather than waiting for GC.
+      try {
+        gl.getExtension?.('WEBGL_lose_context')?.loseContext();
+      } catch {
+        // A context that cannot be released is left to GC.
+      }
+    }
+    if (linkFails) return true;
     // Probe ran and the driver accepted the pattern. Apple mobile is still
     // quarantined: the probe program is far simpler than Cesium's, and a
     // false negative there costs the entire scene.

src/app/atmosphereCompat.test.mjs

@@ -207,3 +207,15 @@ test('tolerates a scene with no fog object', () => {
   assert.equal(applyModelAtmosphereWorkaround({}, {}), false);
   assert.equal(applyModelAtmosphereWorkaround(null, {}), false);
 });
+
+test('releases the throwaway probe context after probing', () => {
+  let lost = 0;
+  const gl = fakeGl({ linkOk: true });
+  gl.getExtension = (name) =>
+    name === 'WEBGL_lose_context' ? { loseContext: () => (lost += 1) } : null;
+  shouldDisableModelAtmosphere({
+    navigatorLike: LINUX_DESKTOP,
+    createProbeContext: () => gl,
+  });
+  assert.equal(lost, 1, 'probe context must not linger until GC');
+});