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]>

scripts/qa-street-level.mjs

@@ -1255,7 +1255,30 @@ async function main() {
               .catch(() => null);
             if (!handle && !fixtures) return skip('no Panoramax line in view');
             assert.ok(handle, 'a Panoramax line is pickable');
-            const at = await handle.jsonValue();
+            let at = await handle.jsonValue();
+            if (fixtures) {
+              // Click the top line where the other sequence's pictures are:
+              // the nearest picture is then the other's, and only the line
+              // click's own-sequence lookup opens the clicked line's.
+              const others = panoramaxPictures()
+                .filter((p) => p.sequenceId !== at.id)
+                .slice(40, 100)
+                .map((p) => [p.lon, p.lat]);
+              const aimed = await page
+                .waitForFunction(
+                  findPickPoint,
+                  { timeout: 60_000, polling: 500 },
+                  {
+                    prefix: 'pnx:seq:',
+                    id: at.id,
+                    points: others,
+                    billboardIds: null,
+                  },
+                )
+                .catch(() => null);
+              assert.ok(aimed, 'the line is pickable over the other’s pictures');
+              at = await aimed.jsonValue();
+            }
             const parked = await camera();
             await page.mouse.click(at.x, at.y);
             await page.waitForFunction(
@@ -1298,8 +1321,8 @@ async function main() {
               else
                 assert.equal(
                   caption,
-                  'Licence Ouverte 2.0',
-                  'an account named by an email address is not shown',
+                  'via panoramax.openstreetmap.fr · Licence Ouverte 2.0',
+                  'an account named by an email address is not shown; the instance is',
                 );
               const pictures = panoramaxPictures().filter(
                 (p) => p.sequenceId === street.sequenceId,