Merge upstream/main into pr/google-street-view

Conflicts with upstream's Street Level provider composition and share-state
codec, resolved:

- Street View's switch moves from its own share option (`g`) to upstream's
  provider-switch field (`r`, e.g. `0.r.google-1`); a link without it keeps
  Street View off. Docs and the browser gate follow.
- createApplicationStreetLevel keeps upstream's injectable provider list;
  its default, once the application supplies its Street Level source, is
  Mapillary plus Google Street View. Without that source there are none, as
  upstream intends.
- The coverage hint keeps upstream's empty-composition message and joins
  every switched-on provider's hint otherwise.
- CHANGELOG, README and SECURITY keep both sides' entries.

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

scripts/format-scope.json

@@ -36,6 +36,10 @@
   "src/main.js",
   "docs/APPLICATION.md",
   "scripts/qa-application.mjs",
+  "scripts/qa-voice-auth.mjs",
+  "scripts/qa-voice-auth-focus.mjs",
+  "src/codexOauthRealtime.test.mjs",
+  "src/voice/cloudVoiceAuth.test.mjs",
   "scripts/qa-panel-resize.mjs",
   "scripts/qa-panelDrag.mjs",
   "src/tooling/panelResizeQa.test.mjs",