refactor(street-level): remove the remaining duplicated code and fakes

A duplicate scan of every module the PR adds (repeated 4-line blocks,
normalised) after gekh's dedup round left these:

- glyphs.js: the cone, ring and position glyphs share cachedGlyph(), wedge(),
  ring() and dot(). Checked with a recording canvas: all 20 draw calls keep
  the same path and fill/stroke state, so the glyphs are pixel-identical.
- panelPositionControls.js: one placeAt() for the three places that pin a
  panel's top-left corner as a fixed window.
- tiles.js: one warn() for the three background-failure logs.
- Tests: src/testSupport/streetLevelFakes.mjs holds the provider snapshot
  (uiState + presentation tests), the stand-in provider (core + controls
  tests) and one real-ray pinhole camera (view + coverage tests, which had
  each written their own). The coverage line-of-sight test still fails when
  refresh() stops passing its focus.
- qa-street-level.mjs: one waitForCoverage() for the five copies of the
  "on, drawn, settled, not key-gated" wait.

No behaviour change: unit 5862 pass, fixture gate 16/16, panel gate 5/5.

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

src/ui/panelPositionControls.js

@@ -72,6 +72,14 @@ function fitWindowExtent(value, minimum, viewportExtent) {
  * Only a mouse or pen lifts and resizes a portable panel. On a phone the
  * rail is a scroll container, so a finger on a header is a swipe.
  */
+/** Pin a panel's top-left corner at (left, top) as a fixed window would sit. */
+function placeAt(panelEl, left, top) {
+  panelEl.style.left = `${left}px`;
+  panelEl.style.top = `${top}px`;
+  panelEl.style.right = 'auto';
+  panelEl.style.bottom = 'auto';
+}
+
 function isPrecisePointer(event) {
   const pointerType = event.pointerType || 'mouse';
   return pointerType === 'mouse' || pointerType === 'pen';
@@ -433,10 +441,7 @@ export class PanelPositionControls {
             Math.round(pos.top),
             panelEl,
           );
-      panelEl.style.left = `${left}px`;
-      panelEl.style.top = `${top}px`;
-      panelEl.style.right = 'auto';
-      panelEl.style.bottom = 'auto';
+      placeAt(panelEl, left, top);
       if (panelId === 'pp-toggles') {
         this._pinPanelToRight(panelEl);
       }
@@ -513,10 +518,7 @@ export class PanelPositionControls {
    */
   _liftPanelOut(panelId, panelEl, rect = panelEl.getBoundingClientRect()) {
     if (panelEl.classList.contains('panel-floating')) return false;
-    panelEl.style.left = `${Math.round(rect.left)}px`;
-    panelEl.style.top = `${Math.round(rect.top)}px`;
-    panelEl.style.right = 'auto';
-    panelEl.style.bottom = 'auto';
+    placeAt(panelEl, Math.round(rect.left), Math.round(rect.top));
     if (!panelEl.classList.contains('collapsed')) {
       panelEl.style.width = `${Math.round(rect.width)}px`;
     }
@@ -580,10 +582,7 @@ export class PanelPositionControls {
       const offsetX = event.clientX - rect.left;
       const offsetY = event.clientY - rect.top;
 
-      panelEl.style.left = `${rect.left}px`;
-      panelEl.style.top = `${rect.top}px`;
-      panelEl.style.right = 'auto';
-      panelEl.style.bottom = 'auto';
+      placeAt(panelEl, rect.left, rect.top);
       panelEl.classList.add('panel-dragging');
       this._promotePanelZ(panelEl);
 

src/ui/streetLevelControls.test.mjs

@@ -9,6 +9,7 @@ import {
   REGISTERED_LAYER_IDS,
   encodeLayerStateParams,
 } from '../data/layerState.js';
+import { fakeStreetLevelProvider } from '../testSupport/streetLevelFakes.mjs';
 
 /* ── A small DOM: just what the panel controls touch ───────────────────── */
 
@@ -296,47 +297,8 @@ const settle = () => new Promise((resolve) => setTimeout(resolve, 0));
 /* ── A Street Level layer with one stand-in provider ───────────────────── */
 
 function standInProvider() {
-  const filters = [];
-  return {
-    filters,
-    def: {
-      id: 'mapillary',
-      name: 'Mapillary',
-      label: 'MAPILLARY',
-      requiresKeyId: null,
-      pickPrefix: 'mly:',
-      colors: { coverage: '#05cb63' },
-      credit: { html: 'Mapillary' },
-      create: () => ({
-        status: async () => ({ configured: true }),
-        init() {},
-        activate() {},
-        deactivate() {},
-        destroy() {},
-        refreshCoverage() {},
-        setFilter: (filter) => filters.push(filter),
-        coverageStats: () => ({
-          count: 0,
-          zoom: null,
-          kind: null,
-          loading: false,
-          hint: '',
-          error: null,
-          keyRequired: false,
-        }),
-        handlePick: () => false,
-        nearestImage: async () => null,
-        viewer: {
-          mount: async () => {},
-          open: async () => {},
-          close() {},
-          unmount() {},
-          resize() {},
-          onPose: () => () => {},
-        },
-      }),
-    },
-  };
+  const def = fakeStreetLevelProvider({ html: 'Mapillary' });
+  return { filters: def.filters, def };
 }
 
 /** Every other registered layer, as a module with no options. */

src/ui/streetLevelPresentation.test.mjs

@@ -5,22 +5,9 @@ import {
   SINCE_STOPS,
   sinceStopIndex,
 } from './streetLevelPresentation.js';
+import { providerSnapshot } from '../testSupport/streetLevelFakes.mjs';
 
-const provider = (overrides = {}) => ({
-  id: 'mapillary',
-  name: 'Mapillary',
-  label: 'MAPILLARY',
-  on: true,
-  configured: true,
-  keyRequired: false,
-  requiresKeyId: 'mapillary',
-  loading: false,
-  count: 0,
-  hint: '',
-  error: null,
-  color: '#05cb63',
-  ...overrides,
-});
+const provider = providerSnapshot;
 
 function snapshot(overrides = {}) {
   const base = {