feat(directions): keyless A→B directions with turn-by-turn steps and FLY (#564)

Supersedes #219 by @spcpza, ported onto the current component layout with fixes from review.

Verified before merge: format, package boundaries, unit suite, build, and the browser tracking suite; a browser harness for the change where one applies; adversarial review applied.

Co-authored-by: spcpza <[email protected]>

src/data/manager.js

@@ -14,6 +14,17 @@ export class DataLayerManager extends LayerLifecycle {
   _refreshTogglePanel() {
     this._presentation.refresh();
   }
+
+  /**
+   * Repaint the toggle panel now. For layers whose data arrives outside their
+   * manager tick (camera-driven loads such as Transit's proximity polls), so a
+   * row shows its count when the data lands instead of at the next interval.
+   * One DOM pass; skipped while the document is hidden.
+   */
+  refreshLayerStats() {
+    this._refreshTogglePanel();
+  }
+
   _buildMetaText(layer) {
     return this._presentation.panel._buildMetaText(layer);
   }