refactor(street-level): one provider, no orbit overview, no prewarm, simpler tile choice

The layer now owns its Mapillary parts directly: the provider registry,
pick router, multi-provider UI summary, params codec helper and provider
context are gone. createStreetLevelLayer({ source }) builds coverage,
sequences, the nearest-image lookup and the MapillaryJS viewer itself; a
single providerOn switch keeps the share link's `mapillary` option (off
draws nothing), and getParams/setParams keep { mapillary, pano, sinceDays }.

No z0-5 overview points: above 60 km nothing is drawn and the panel says to
zoom in; the proxy now serves only coverage z11-14. Tiles come from the
visible ground within range of the camera, ranked from the ground under it
(no line-of-sight ranking or near-range padding). MapillaryJS loads on the
first photo; viewer prewarm is removed. Key status, a rejected key and a
rate limit share one `blocked` state on coverage.

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

server/providers/mapillary/constants.js

@@ -5,12 +5,12 @@ export const MAPILLARY_TILE_HOST = 'https://tiles.mapillary.com/maps/vtp';
 
 /** Public tile layer names this proxy exposes, mapped to Mapillary's ids. */
 export const TILE_LAYERS = Object.freeze({
-  // Region-sized z6–10 tiles are refused; the app never asks for them. The
+  // Only the street zooms the app draws (z11–14); the rest are refused. The
   // z14 `image` layer is ~98% of a tile and unused (positions come from the
   // graph API), so it is dropped in transit.
   coverage: Object.freeze({
     upstream: 'mly1_public',
-    zoomRanges: Object.freeze([Object.freeze([0, 5]), Object.freeze([11, 14])]),
+    zoomRanges: Object.freeze([Object.freeze([11, 14])]),
     dropLayers: Object.freeze(['image']),
   }),
 });