fix(street-level): Panoramax UX QA — connection budget, coverage to 60 km, Esc, attribution

From a UX QA round in the browser against the live API:
- A line click could time out while coverage loaded: the meta-catalogue
  speaks HTTP/1.1 only (six connections), and six tiles plus four
  searches queued the lookup behind megabyte tiles. Tiles now take
  three connections and searches two; a search that timed out is asked
  once more.
- Between 30 and ~100 km Paris read as empty: the density grid is ~10 km
  a cell. Lines now draw to 60 km (z10), as Mapillary's do; above, dots
  grow with the pictures they stand for.
- Esc in the docked viewer collapsed the whole panel instead of clearing
  the sequence the panel says it clears (shared photo viewer: KartaView
  too). The viewer now offers Esc to the provider first; expanded, the
  dialog keeps it.
- A picture whose producer is an email address is credited to the
  instance holding it (its `via` host), so Licence Ouverte pictures name
  their source.
- Empty states say why: "no Panoramax photos here match the filters"
  when the filter hid every line, and nothing to zoom into over empty
  sea. Wording follows KartaView's ("photos", "click a line for its
  nearest photo").

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

src/layers/streetLevel/lineCoverage.js

@@ -95,6 +95,7 @@ export function meshBoxInRange(box, centre) {
  * @param {LineCoverageTuning} options.tuning
  * @param {{keyRejected?: string, rateLimited: string, tooHigh?: string}} options.messages
  * @param {(sequence: object, filter: object) => boolean} [options.passes]  Whether the imagery filter keeps a line or point.
+ * @param {(point: object) => number} [options.overviewPointSize]  An overview point's size in pixels (default `tuning.overviewPointPx`).
  */
 export function createLineCoverage({
   state,
@@ -106,6 +107,7 @@ export function createLineCoverage({
   tuning,
   messages,
   passes = passesImageryFilter,
+  overviewPointSize = null,
 }) {
   const { render } = state.services;
   const perTileSequenceCap = Math.floor(tuning.maxSequences / tuning.maxTiles);
@@ -427,7 +429,7 @@ export function createLineCoverage({
         collection.add({
           position: Cesium.Cartesian3.fromDegrees(point.lon, point.lat),
           color: tint,
-          pixelSize: tuning.overviewPointPx,
+          pixelSize: overviewPointSize?.(point) ?? tuning.overviewPointPx,
           // Google 3D terrain and clouds must not hide the near side's dots;
           // the horizon cull hides the far side's, which this lets through.
           disableDepthTestDistance: Number.POSITIVE_INFINITY,