feat(street-level): Street View polish — name, filters, legend, marker

- The chip reads GOOGLE STREET VIEW (and its caption link likewise).
- Providers declare the imagery filters they honour (`filters`, default
  pano + since). Street View declares none: every panorama is 360° and it
  draws no coverage to thin, so its lookups ignore the filters and the
  panel hides IMAGERY and SINCE while it is the only lit provider.
- The legend lists only providers that draw coverage lines, with
  Selected only beside one: Street View alone shows no legend.
- Providers may pick their on-globe marker (`marker`); Street View's is a
  Google-blue field-of-view cone from a white-ringed dot, in place of
  GEV's amber pin, and switches back for a Mapillary photo.

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

src/ui/styles/street-level.css

@@ -229,7 +229,11 @@ button.sl-status:focus-visible {
   border-radius: 999px;
 }
 
-.sl-seg[hidden] {
+.sl-seg[hidden],
+.sl-controls[hidden],
+.sl-filters[hidden],
+.sl-since[hidden],
+.sl-legend[hidden] {
   display: none;
 }