Merge upstream/main: Street View rework meets i18n

Upstream's Street View rework (second imagery provider, one source at a
time, OPEN STREET VIEW button, key-alternative guidance) rewrote exactly
the street-level regions this branch localizes.

Resolved as upstream logic + re-applied localization:

- keySetupCore: new unlock copy kept as msg() data; added
  keySetupAlternativeKeyNames() returning machine values (registry key
  names) so key-setup core stays English while presentation localizes.
- New src/ui/keyGuidance.js: localized key-guidance composer shared by
  layerPanel and streetLevelPresentation (requirement sentence plus the
  "or light X to use your Y key" alternatives tail, placeholders only).
- streetLevelPresentation: keyGuidance()/presentNearest()/presentMeta
  relocalized (t/tn + formatNumber instead of toLocaleString);
  renderModes and month-precision dates kept from upstream.
- layer-panels.html: upstream row ids, sl-meta-row and the new button
  kept, data-i18n hooks re-applied (incl. OPEN STREET VIEW fallback).
- es/ru catalogs: 13 new keys, stale unlock key replaced in place.

npm run i18n: complete for es and ru. npm test: 6345/6347; the one
failure (devFreshDotenv provenance) also fails on plain upstream/main
and on the pre-merge tip here - this machine leaks OPENAI_API_KEY into
spawned children with a replaced env, so it is environmental.

src/streetLevelMarkup.test.mjs

@@ -256,3 +256,14 @@ test('the Cyber theme frames the Street Level panel like its rail peers (P3)', (
   // A theme header rule must be able to outrank the panel's own.
   assert.doesNotMatch(panelCss, /#street-level-panel \.panel-header/);
 });
+
+test('OPEN STREET VIEW keeps its width beside a long coverage line', () => {
+  // .scene-btn grows and shrinks (flex: 1) and loads after this stylesheet:
+  // only a more specific rule keeps the button from being squeezed.
+  assert.match(css, /\.scene-btn \{[^}]*flex: 1;/);
+  assert.match(
+    panelCss,
+    /\.sl-meta-row \.sl-nearest-btn \{\s*flex: 0 0 auto;\s*\}/,
+  );
+  assert.match(panelCss, /\.sl-meta-row \.sl-meta \{[^}]*min-width: 0;/);
+});