fix(street-level): own the framing flight and the nearest-photo lookup

From the IC8 review of #768, each with tests that fail before:

- P1: closing a photo, switching the layer off or destroying it stops the
  1.6 s framing flight toward that photo. The flight is claimed with a
  token before flyToBoundingSphere and released by its complete/cancel
  callbacks, so cancelFraming() calls camera.cancelFlight() only while
  the flight is still Street Level's: a newer navigation flight (a search
  result, a scene) is never cancelled. Turning FOLLOW on also stops it, so
  the tween cannot overwrite the follow view.
- P2: an older nearest-photo lookup can no longer replace a newer choice.
  The core owns one AbortController per lookup, aborted by a newer lookup,
  a direct open or cone click, closing the viewer, disable and destroy;
  the signal reaches source.nearestImages through the provider, and an
  aborted lookup never surfaces as an error.

Co-Authored-By: Claude Opus 5.5 <[email protected]>

src/layers/streetLevel/viewerHost.js

@@ -153,9 +153,13 @@ export function createViewerHost({ state, parts }) {
     return true;
   }
 
-  /** Close the image; the mounted adapter stays warm for the next open. */
+  /**
+   * Close the image; the mounted adapter stays warm for the next open. The
+   * globe stops flying toward it too (unmount closes, so layer off does).
+   */
   function close() {
     openSeq++;
+    parts.follow.cancelFraming();
     active?.adapter.close();
     Object.assign(state.street, freshStreet());
     parts.marker.clear();