fix(street-level): settle loading on pan, keep zoom 0, drop late poses

Fixes from gekh's re-review of 061d269, each with a regression test that
fails on the old code:

- A pan that drops a tile still loading now settles the loading count
  (the aborted request no longer owns its key, so its `finally` never
  did), and purges the previous zoom's tiles once nothing is pending.
  LOADING no longer sticks on the status pill and chip.
- Zoom 0 (above 15,000 km) is a zoom: `zoom == null` instead of `!zoom`.
- A pose that arrives after a photo was closed is dropped, in the
  MapillaryJS adapter and in the viewer host, so the marker and sequence
  selection do not come back.
- Ground casting passes the tile's signal to the terrain request, so a
  cancelled tile stops its height batch instead of holding the queue.
- The server's in-memory tile cache honours the 24 h TTL like the disk.
- The viewer's one-time resize runs for every photo, not just the first.

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

src/tooling/mapillaryProvider.test.mjs

@@ -202,6 +202,24 @@ test('fetchTile serves from memory after one upstream fetch and strips the image
   }
 });
 
+test('a tile held in memory past the 24 h TTL is fetched again', async (t) => {
+  const tile = { layer: 'coverage', z: 9, x: 3, y: 3 };
+  await withDeferredUpstream([tile], async ({ upstream, settle }) => {
+    const first = fetchTile(tile);
+    await settle();
+    upstream[0].release();
+    assert.equal((await first).source, 'upstream');
+    assert.equal((await fetchTile(tile)).source, 'memory');
+    const now = Date.now();
+    t.mock.method(Date, 'now', () => now + 25 * 60 * 60 * 1000);
+    const again = fetchTile(tile);
+    await settle();
+    assert.equal(upstream.length, 2, 'neither cache answers a stale tile');
+    upstream[1].release();
+    assert.equal((await again).source, 'upstream');
+  });
+});
+
 /**
  * A deferred upstream for in-flight tests: every fetch waits until released,
  * and records whether its signal was aborted. Coordinates use z9, which the