fix(street-level): IC8 follow-ups for Google Street View

- An open after a failed one is no longer failed by the old panorama's
  status: only status_changed can reject; position_changed only resolves.
- A nearest lookup aborted, timed out or refused while Google's script
  loads no longer sends its getPanorama request once the script arrives.
- A panorama-details lookup that never answers times out after 10 s,
  cools down and retries; an unmount releases lookups in flight, and
  their late answers are dropped.
- Every Maps loader on a page shares one script load and ready callback,
  and either can retry a failed script.
- OPEN STREET VIEW aimed at the sky opens nothing and says to aim at a
  street, instead of looking up the camera footprint.

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

src/layers/streetLevel/policy.js

@@ -42,3 +42,7 @@ export const FOLLOW_EYE_HEIGHT_M = 2.4;
  * (Google Street View) only from this close: from higher up it is a misclick.
  */
 export const GROUND_CLICK_MAX_HEIGHT_M = 3_000;
+
+/** OPEN STREET VIEW aimed at the sky: it opens what the user aims at, or nothing. */
+export const AIM_AT_GROUND_MESSAGE =
+  'Aim the middle of the view at a street to look for imagery there';