feat(street-level): "show me X on Street View" action, street_level view field and sl= links

show_street_level (voice and typed) flies to a place and opens its nearest
street-level photo from Google Street View, Mapillary, KartaView or
Panoramax; Street View switches to Google 3D first. The view model gains a
street_level field, share links carry sl=<source>,<lat>,<lon>, and
show_in_gods_eye_view can open a photo. A plain sl=google link only arms the
point and waits for OPEN, so it never bills a key without a click.

Embed pages show an open photo in an overlay that Esc closes. On-screen
strings are translated into es, ru, zh-CN and zh-Hant. Covered by unit tests
and three new steps in the Street Level browser suite.

src/voice/deixis.js

@@ -330,6 +330,7 @@ function resolveCropPixels(args, { imageFrame, cameraKey }) {
 const RESOLVERS = Object.freeze({
   track_entity: resolveTrack,
   fly_to_location: resolveFly,
+  show_street_level: resolveFly,
   get_entity_context: resolveContext,
   analyst_query: resolveAnalyst,
   annotate_map: resolveAnnotate,