fix(street-level): address gekh's review of #768

P0
- tileMath: lonToTileX(180) wrapped to column 0, so a whole-world view at
  z1 loaded only the western column; 180 is now the last column.
- coverage.loadTile: a superseded request (after a retire or clear) still
  deleted the newer request's pending entry and loading count in `finally`,
  letting a duplicate load attach lines that nothing could remove. Only the
  request that still owns the key attaches its tile or settles the key.

P1
- view/tileMath: a view across the date line read as a ~358 deg box and
  loaded tiles on the far side of the globe. visibleBbox now returns
  west > east for such views and tilesForBbox splits them at +/-180;
  viewCentre averages across the line.
- decode: the parts of a multi-line sequence were joined into one line,
  drawing straight segments over capture gaps. Each part is now its own
  line (`parts`); later parts carry `~n` in their pick id, and picking or
  recolouring any part acts on the whole sequence.
- viewerHost: a prewarmed MapillaryJS viewer was never destroyed, leaking
  its WebGL context. Prewarmed adapters are tracked and released on
  unmount, at once when the layer went off mid-load, and per provider when
  only that provider is switched off.
- nearestImage took the first record the API returned; it now takes the
  closest one that passes the filter.

P2
- groundCast: the cache was cleared after a request counted its corners,
  dropping ones it relied on; it is now cleared first.
- streetLevelControls: the viewer was resized on every render (every frame
  while a panorama is dragged); the ResizeObserver handles size changes and
  the viewer is resized once when it opens. The legend now rebuilds when its
  entries change, not only their count.
- panelPositionControls: the portable-panel paths this PR added called the
  CCTV viewport sync directly; they go through onPanelResized, which the
  shell routes to CCTV. The "Compose camera panel controls" JSDoc is back on
  _initCctvPanel.

New tests: zoom-1 columns, date-line tiles and bbox, multi-part decode and
part pick ids, nearest image, prewarmed viewer release, and the cache
ordering (fails on the old order).

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

src/ui/streetLevelControls.js

@@ -366,7 +366,13 @@ export class StreetLevelControls {
         el.sinceRange.setAttribute('aria-valuetext', view.since.label);
       }
     }
-    if (el.legend && el.legend.childElementCount !== view.legend.length) {
+    // Rebuild when the swatches change, not only their count: one provider
+    // can replace another with the same number of entries.
+    const legendKey = view.legend
+      .map((entry) => `${entry.key}:${entry.color}:${entry.label}`)
+      .join('|');
+    if (el.legend && this._legendKey !== legendKey) {
+      this._legendKey = legendKey;
       el.legend.replaceChildren(
         ...view.legend.map((entry) => {
           const item = document.createElement('li');
@@ -406,7 +412,11 @@ export class StreetLevelControls {
       if (viewer.link) el.imageLink.href = viewer.link;
       if (viewer.linkLabel) el.imageLink.textContent = viewer.linkLabel;
     }
-    if (state.street.open) this.layer.resizeViewer?.();
+    // Size changes reach the viewer through the ResizeObserver; resizing on
+    // every render ran each frame while a panorama was dragged. Opening is the
+    // one moment the element may not have reported a size yet.
+    if (state.street.open && !this._viewerWasOpen) this.layer.resizeViewer?.();
+    this._viewerWasOpen = state.street.open === true;
   }
 
   _renderMeta(view) {