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]>

package.json

@@ -260,7 +260,6 @@
       "node": "./server/providers/mapillary.js"
     },
     "./layers/street-level": "./src/layers/streetLevel/index.js",
-    "./layers/street-level/mapillary": "./src/layers/streetLevel/providers/mapillary/index.js",
     "./layers/street-level/mapillary/source": "./src/layers/streetLevel/providers/mapillary/source.js",
     "./tools": "./src/tools/index.js",
     "./tools/mcp": "./src/tools/mcp/index.js",