fix(street-level): Panoramax IC8 review — line geometry budget, caches, attribution, tests

From a five-lens IC8 review (correctness, security, tests with mutation
testing, performance, UX):
- P0: over Paris at 12–60 km the unsimplified z10–z12 lines sent ~2M
  points to Cesium's ground-polyline builder (gigabytes of geometry; the
  tab hung). decode.js now simplifies lines (Douglas–Peucker, 4 tile
  units: 6–10% of the points), and lineCoverage gains an opt-in point
  budget (`maxPoints`, 10,000 a tile for Panoramax).
- Decoded coverage tiles are kept (KartaView's tile cache moves to the
  shared tileCache.js); a sequence's z15 picture lists are kept and load
  on their own connection; cones know their tiles from the start of a
  load, so a picture opening meanwhile re-centres them and ‹ › no longer
  restarts the load.
- The HD panorama loads only for the expanded viewer (a docked one on a
  dense screen asked for 3 MB originals) and is aborted when another
  photo opens; picture files over 48 MB or 16,384 px are refused; a
  bitmap no renderer took after a context loss is closed.
- A nearest lookup survives one of its two searches failing; only a
  timeout is retried; offline reads as unreachable; Retry-After is
  capped at five minutes; the search box stays on the map at ±180°;
  cones near both edges of a narrow (high-latitude) tile read both.
- Every producer is credited (app and photographer); with none to name,
  the caption says "via <instance>" rather than crediting the host.
- Esc anywhere in the docked viewer (toolbar, caption) clears the
  sequence before the panel takes it. A filter that hides every density
  dot says so; wording aligned ("coverage", "photo").
- Tests for every surviving mutant (Esc consumed, keepOrder and dot-size
  wiring, licence in the core, limiter aborts, radius floor, bbox corner,
  first-producer-only, byte and size caps), a limiter test, and a gate
  fixture that answers box searches and leaves out pictures facing away;
  the gate now clicks over the other sequence's pictures, so only the
  line click's own-sequence lookup can pass.

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

src/ui/streetLevelPresentation.test.mjs

@@ -539,3 +539,22 @@ test('KEY REQUIRED points at Street View when it would draw with the Google key'
   assert.equal(plain.status.text, 'KEY REQUIRED');
   assert.notEqual(plain.meta, guidance);
 });
+
+test('the caption names an image’s own licence after its author, and leaves it out when there is none', () => {
+  const caption = (street) =>
+    presentStreetLevelPanel({
+      enabled: true,
+      providers: [],
+      coverage: {},
+      legend: [],
+      filter: {},
+      sequence: {},
+      street: { open: true, imageId: '1', ...street },
+    }).viewer.captionLeft;
+  assert.equal(
+    caption({ creator: 'Fixture Mapper', license: 'CC BY-SA 4.0' }),
+    'Image by Fixture Mapper · CC BY-SA 4.0',
+  );
+  assert.equal(caption({ license: 'Licence Ouverte 2.0' }), 'Licence Ouverte 2.0');
+  assert.equal(caption({ creator: 'Someone' }), 'Image by Someone');
+});

src/ui/styles/street-level.css

@@ -651,7 +651,7 @@ button.sl-status:focus-visible {
   pointer-events: none;
 }
 
-/* White on #ff6f00 is 2.9:1; the darker orange behind ‹ › is 4.6:1. */
+/* White on #ff6f00 is 2.8:1; on the darker orange behind ‹ › it is 5.1:1. */
 .sl-photo-viewer[data-provider='panoramax'] {
   --sl-photo-ring: var(--sl-panoramax);
   --sl-photo-fill: var(--sl-panoramax-fill);
@@ -720,7 +720,8 @@ button.sl-status:focus-visible {
 }
 
 /* Nothing to step through until a photo shows. */
-.sl-photo-viewer:not([data-kind='flat']):not([data-kind='pano']) .sl-photo-step {
+.sl-photo-viewer:not([data-kind='flat']):not([data-kind='pano'])
+  .sl-photo-step {
   display: none;
 }