fix(street-level): re-check an unknown key, Esc leaves full screen, say why a view is empty

- A failed or missing key status is asked again on the next switch-on, and
  the check gives up after 10 s instead of holding LOADING forever.
- Waiting for the key status reads as LOADING while the layer is on.
- Esc shrinks the photo in full screen too, before the panel's own Esc.
- Destroying the panel with the iPhone popover open leaves no popover behind.
- An empty view says whether the filter emptied it.
- A freed upstream tile slot passes straight to the oldest waiter.

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

src/layers/streetLevel/providers/mapillary/coverage.test.mjs

@@ -220,11 +220,16 @@ test('the key status gates coverage: nothing before it answers, nothing without
     state.coverage.blocked = 'status';
     coverage.refresh();
     assert.equal(source.calls.length, 0, 'nothing before the status answers');
+    assert.equal(coverage.stats().loading, true, 'waiting reads as loading');
+    state.enabled = false;
+    assert.equal(coverage.stats().loading, false, 'but not while off');
+    state.enabled = true;
     coverage.setKeyStatus(configured);
     if (configured)
       assert.equal(source.calls.length, 1, 'coverage loads once it is known');
     else {
       assert.equal(source.calls.length, 0, 'a key-less install never asks');
+      assert.equal(coverage.stats().loading, false);
       assert.equal(coverage.stats().keyRequired, true);
       assert.equal(coverage.stats().keyRejected, false);
       coverage.unblock();