test(street-level): coverage race, camera framing and panel-control tests

From the test-engineering review of #768: the rendering and panel code had
thin unit coverage (coverage.js 29% of lines, sequences/viewer/selection
~30%, cameraFollow 50%, streetLevelControls only source-text checks), and
two shipped bugs were caught only by the manual browser gate.

- coverage.test.mjs drives the real createCoverage against a fake scene and
  a source whose tile requests the test resolves. It reproduces gekh's P0 #2:
  a request superseded by retire() finishes after a newer one for the same
  tile. Without the ownership checks it drops the newer request's key and a
  refresh starts a duplicate whose lines nothing can remove (fails on the old
  loadTile, passes now). It also covers the draped-to-cast swap keeping both
  line sets on the globe until the cast one is built and clear() removing
  both mid-swap, and a tile with nothing castable not being rebuilt.
- coverageFixture.mjs encodes Mapillary-shaped coverage tiles (sequence
  lines, overview points) from lon/lat; the tests and the hermetic gate use it.
- cameraFollow.test.mjs pins the underground-camera fix: a -14,886 m sample
  is ignored for bare earth, a plausible sample wins, and following stands at
  eye height. Three of the four fail on the pre-fix module (the first reports
  "centre at -14884 m").
- streetLevelControls.test.mjs is a contract test through the real
  DataLayerManager and LayerStateCoordinator: a 360 deg click and a SINCE
  release reach the durable layer state and the encoded share link under
  Street Level's token. Against a stand-in layer it also covers the chip rule
  (darkening the last lit chip turns the layer off, provider kept on; lighting
  a dark chip is a user params request, then enable), the legend rebuilding
  on a same-count swap (review #9) and the viewer resizing only on open
  (review #8). With the old direct-to-layer routing, three of these fail,
  including both share-link tests.

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

scripts/format-scope.json

@@ -908,6 +908,10 @@
   "src/layers/streetLevel/view.test.mjs",
   "src/layers/streetLevel/providers/mapillary/provider.test.mjs",
   "src/layers/streetLevel/providers/mapillary/decode.test.mjs",
+  "src/layers/streetLevel/providers/mapillary/coverage.test.mjs",
+  "src/layers/streetLevel/providers/mapillary/coverageFixture.mjs",
+  "src/layers/streetLevel/cameraFollow.test.mjs",
+  "src/ui/streetLevelControls.test.mjs",
   "src/ui/panelDock.test.mjs",
   "src/layers/streetLevel/viewerHost.test.mjs",
   "src/layers/streetLevel/index.test.mjs",