refactor(street-level): trim QA, tests, styles and docs

The browser gate is one pass over the remaining flows: rail strip and
expand, coverage with fixtures, the ON/OFF pill, 360° and SINCE filters,
KEY REJECTED, nearest photo with caption, × close, phone fit, keyless
KEY REQUIRED on a second page and no page errors. Panel controls are
pressed through the DOM; pick-point search, line/cone clicks, the
framing-cancel, reload/share and status-route probes, the second
viewport and pointer-settling retries are gone (unit tests cover them).

Tests that pinned constants, copy, CSS or source text, or repeated
another test, are removed or merged. CSS loses an unused variable and
duplicate rules. Docs describe the slimmed feature; unused exports and
the layer's dead setCoverageFilter/refreshCoverage surface are removed.

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

CHANGELOG.md

@@ -3,17 +3,15 @@
 ## [Unreleased]
 
 - Street Level: Mapillary street-level imagery modelled on the iD editor's
-  photo overlay (free client token, CC BY-SA 4.0 imagery). One right-rail panel
-  holds an ON/OFF pill, 360°/flat and captured-since filters, a legend, and an
-  embedded viewer with full-screen EXPAND and FIT/FILL. Coverage lines (below
-  60 km; from orbit the panel says to zoom in) and image cones are draped on
-  the terrain and on Google 3D tiles; MapillaryJS loads on the first photo,
-  and opening one frames it with one camera flight.
-  Share links carry the Mapillary switch, the filters and the panel's collapsed
-  state. A server proxy adds the token to Mapillary coverage tiles, drops
-  their unused image layer and keeps them in memory (24 h); it refuses
-  cross-site requests and rate-limits per IP, and the panel stops asking when
-  Mapillary rejects the token or rate-limits.
+  photo overlay (free client token, CC BY-SA 4.0 imagery). A docked right-rail
+  panel holds an ON/OFF pill, 360°/flat and captured-since filters, a legend
+  and an embedded viewer with full-screen EXPAND and FIT/FILL. Coverage lines
+  (below 60 km) and image cones drape on the terrain and Google 3D tiles;
+  opening a photo frames it with one camera flight. Share links carry the
+  switch, the filters and the panel's collapsed state. A server proxy keeps
+  the token server-side, trims coverage tiles and caches them in memory for
+  24 h; it refuses cross-site requests and rate-limits per IP. The panel reads
+  KEY REQUIRED without a token and KEY REJECTED when Mapillary refuses it.
 
 - Add Norway's road cameras from Statens vegvesen as a CCTV pack. The camera
   list is one keyless GeoJSON request to the agency's OGC API view of its