test(street-level): close the mutation survivors; Esc in rich text

A mutation review left 18 earlier survivors; each now has a test that
fails with the mutant applied:

- the expanded viewer returns into the panel on shrink, close and destroy
  (the fake DOM had no parentNode, so reinsertion was never exercised); the
  fake DOM gains offsetParent and a MutationObserver that honours its
  options, and a <body> child added while expanded goes inert;
- each pose moves the marker, drives FOLLOW and selects a new sequence;
  close() retires an open still mounting or opening; a provider toggled
  while the layer is off activates nothing; the adapter drops late and
  superseded poses;
- share-link defaults: "any date" (0 days), the codec max pinned to the
  filter's MAX_SINCE_DAYS (layerState cannot import it across package
  boundaries, so a test ties the two), Mapillary on when a link omits it;
- Esc that something else handled, or typed in a field, keeps the
  selection; a key problem outranks LOADING on the pill;
- the marker's terrain height (mesh, DEM, clamp then re-place);
- proxy: LRU memory cache and its half-budget rule, Retry-After capped,
  a request after a cancelled fetch starts a fresh one;
- date-line tile ranking with and without focus; the horizon cull idles
  while the camera stands still; the old zoom goes as soon as the new one
  lands; a rate limit holds every refresh inside its wait.

One real bug found and fixed: Esc inside a contenteditable cleared the
selected sequence (selection.js now ignores isContentEditable targets).

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

src/data/layerState.js

@@ -419,6 +419,8 @@ const OPTION_GROUPS = Object.freeze({
       flat: 'f',
     }),
     // "Captured since" as relative days, so a link means the same next year.
+    // The filter's MAX_SINCE_DAYS (streetLevel/policy.js); layerState.test
+    // pins the two together.
     boundedIntegerOption('sinceDays', 's', 0, { min: 0, max: 36500 }),
   ]),
   radio: Object.freeze([