refactor(street-level): trim QA, tests, styles and docs

The browser gate is one pass over the remaining flows: rail strip and
expand, coverage with fixtures, the ON/OFF pill, 360° and SINCE filters,
KEY REJECTED, nearest photo with caption, × close, phone fit, keyless
KEY REQUIRED on a second page and no page errors. Panel controls are
pressed through the DOM; pick-point search, line/cone clicks, the
framing-cancel, reload/share and status-route probes, the second
viewport and pointer-settling retries are gone (unit tests cover them).

Tests that pinned constants, copy, CSS or source text, or repeated
another test, are removed or merged. CSS loses an unused variable and
duplicate rules. Docs describe the slimmed feature; unused exports and
the layer's dead setCoverageFilter/refreshCoverage surface are removed.

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

src/layers/streetLevel/index.test.mjs

@@ -143,18 +143,6 @@ function slowLookups() {
   return { lookups, source: fakeMapillarySource({ nearestImages }) };
 }
 
-test('the layer is Mapillary under the codec keys it has always had', () => {
-  const layer = createStreetLevelLayer({ source: fakeMapillarySource() });
-  assert.equal(layer.id, 'street-level');
-  assert.equal(layer.requiresKeyId, 'mapillary');
-  assert.deepEqual(layer.getParams(), {
-    mapillary: true,
-    pano: 'all',
-    sinceDays: 0,
-  });
-  assert.throws(() => createStreetLevelLayer({ source: {} }), /source/);
-});
-
 test('the CC BY-SA credit shows while Mapillary is on and goes with it', async (t) => {
   const { layer, viewer } = await startLayer(t);
   const shown = () => viewer.credits.map((credit) => credit.html);
@@ -284,7 +272,7 @@ test('a sequence error is withdrawn with the sequence, never the viewer’s own'
   assert.match(layer.getUIState().street.error, /Open the Street Level panel/);
 });
 
-test('closing the photo stops the globe flying to it', async (t) => {
+test('closing the photo, switching the layer off or destroying it stops the framing flight', async (t) => {
   const { layer, viewer } = await startLayer(t, {
     photoViewer: posingViewer(),
   });
@@ -292,35 +280,16 @@ test('closing the photo stops the globe flying to it', async (t) => {
   assert.equal(await layer.openImage('img1'), true);
   assert.equal(viewer.flights.started, 1, 'the photo is framed');
   layer.closeViewer();
-  assert.equal(viewer.flights.cancelled, 1);
-});
+  assert.equal(viewer.flights.cancelled, 1, 'closed');
 
-test('switching the layer off or destroying it stops the framing flight', async (t) => {
-  const { layer, viewer } = await startLayer(t, {
-    photoViewer: posingViewer(),
-  });
-  layer.attachViewerHost({});
-  await layer.openImage('img1');
+  await layer.openImage('img2');
   layer.disable();
-  assert.equal(viewer.flights.cancelled, 1, 'layer off');
+  assert.equal(viewer.flights.cancelled, 2, 'layer off');
 
   layer.enable(viewer);
-  await layer.openImage('img2');
+  await layer.openImage('img3');
   layer.destroy();
-  assert.equal(viewer.flights.cancelled, 2, 'destroyed');
-});
-
-test('closing the photo leaves a newer navigation flight alone', async (t) => {
-  const { layer, viewer } = await startLayer(t, {
-    photoViewer: posingViewer(),
-  });
-  layer.attachViewerHost({});
-  await layer.openImage('img1');
-  assert.equal(viewer.flights.started, 1, 'the photo is being framed');
-  // A search result flies the globe elsewhere before the framing lands.
-  viewer.camera.flyToBoundingSphere(null, {});
-  layer.closeViewer();
-  assert.equal(viewer.flights.cancelled, 0, 'the search flight keeps going');
+  assert.equal(viewer.flights.cancelled, 3, 'destroyed');
 });
 
 test('an older nearest lookup that answers late cannot replace a newer one', async (t) => {
@@ -383,7 +352,13 @@ test('closing the viewer or switching the layer off retires a nearest lookup', a
 });
 
 test('setParams takes "any date" (0 days) and the switch over the current values (share-link defaults)', async (t) => {
+  assert.throws(() => createStreetLevelLayer({ source: {} }), /source/);
   const { layer } = await startLayer(t);
+  assert.deepEqual(layer.getParams(), {
+    mapillary: true,
+    pano: 'all',
+    sinceDays: 0,
+  });
   layer.setParams({ pano: 'flat', sinceDays: 365 });
   assert.equal(layer.getParams().sinceDays, 365);
   layer.setParams({ sinceDays: 0 });