Merge origin/main: Google Street View, KartaView and Panoramax on the slim Street Level

Main gained three imagery providers (Google Street View, KartaView,
Panoramax), shared line-coverage, cone and photo-viewer modules, one source
lit at a time and the translated interface. Their shared modules still
carried what this branch removes, so the merge ports them onto it:

- lineCoverage.js is this branch's coverage.js made provider-neutral
  (draped lines near the ground only, the selection drawn over them, key
  and rate-limit blocking); sequenceCones.js is sequences.js the same way.
  Mapillary, KartaView and Panoramax all build on them; Mapillary moves
  back to providers/mapillary/ beside the others.
- No ground casting, mesh sampling, surface modes, FOLLOW, legend, prewarm,
  orbit overview points (Panoramax's density dots included), stale-tile
  swaps or water-filled point budget come back.
- Kept from main because the new providers need them: requiresMapStack and
  attachMapStackController (Street View on Google 3D only), ground clicks,
  openNearest with an optional provider nearestImage, openImage {frame},
  reportError, the view-cone marker (now an SVG glyph), filters /
  coverageLabel / sinceBasis, OPEN STREET VIEW, keyAlternatives and i18n.
- photoViewer.js treats the viewer as expanded when its wrap is full screen
  or the iPhone popover, as EXPAND now is.
- The fixture browser gate keeps its 8 steps and adds one each for
  KartaView and Panoramax; catalogs, docs, boundaries and format scope
  follow.

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

src/ui/panelChrome.js

@@ -1,4 +1,5 @@
 import { UiLifetime } from './uiLifetime.js';
+import { t, msg } from '../i18n/index.js';
 import { displayPanelScroller } from './displayPanelScroll.js';
 import { PanelPositionControls } from './panelPositionControls.js';
 import { PanelLayoutController } from './panelLayoutController.js';
@@ -306,14 +307,25 @@ export class PanelChrome {
         const panelName =
           panelEl
             .querySelector('.panel-title, .pp-header-label')
-            ?.textContent?.trim() || 'panel';
-        const action = collapsed ? 'Expand' : 'Collapse';
-        btn.title = `${action} ${panelName}`;
-        btn.setAttribute('aria-label', `${action} ${panelName}`);
+            ?.textContent?.trim() || t('panel');
+        const titleKey = collapsed
+          ? msg('Expand {name}')
+          : msg('Collapse {name}');
+        btn.title = t(titleKey, { name: panelName });
+        btn.setAttribute('aria-label', t(titleKey, { name: panelName }));
         if (panelEl.id === 'radio-panel') {
-          const action = collapsed ? 'Expand' : 'Collapse';
-          btn.title = `${action} Radio`;
-          btn.setAttribute('aria-label', `${action} Radio section`);
+          // Radio keeps the wording of its static button (context.html).
+          btn.title = t(
+            collapsed ? msg('Expand Radio') : msg('Collapse Radio'),
+          );
+          btn.setAttribute(
+            'aria-label',
+            t(
+              collapsed
+                ? msg('Expand Radio section')
+                : msg('Collapse Radio section'),
+            ),
+          );
         }
       });
     const dockToggle = panelEl.querySelector(
@@ -323,11 +335,13 @@ export class PanelChrome {
       const panelName =
         panelEl
           .querySelector('.panel-title, .location-toolbar-label')
-          ?.textContent?.trim() || 'panel';
-      const action = collapsed ? 'Expand' : 'Collapse';
+          ?.textContent?.trim() || t('panel');
+      const titleKey = collapsed
+        ? msg('Expand {name}')
+        : msg('Collapse {name}');
       dockToggle.setAttribute('aria-expanded', String(!collapsed));
-      dockToggle.setAttribute('aria-label', `${action} ${panelName}`);
-      dockToggle.title = `${action} ${panelName}`;
+      dockToggle.setAttribute('aria-label', t(titleKey, { name: panelName }));
+      dockToggle.title = t(titleKey, { name: panelName });
     }
     if (panelEl.id === 'radio-panel' && this._contextRadioDetailsBtn) {
       this._contextRadioDetailsBtn.setAttribute(