Satellite ground and real building footprints

- The ground is Esri World Imagery: ~1 m/pixel tiles around the city
  zone, the factory and 300 m either side of the drive between them,
  coarser tiles for the whole region. Tiles are hosted with the game
  (public/imagery, scripts/fetch-imagery.mjs), stream in near the camera,
  are cached by the service worker as visited, and replace the drawn
  roads and land areas
- ~141,500 Microsoft building footprints (ODbL) join OSM's ~4,000 in a
  compact delta-encoded file (public/data/buildings.bin, built by
  scripts/build-buildings.mjs). Heights are estimated from footprint
  area and land use, with industrial halls outside the ring road.
  Buildings are built in 500 m blocks as the camera approaches
- Caddy compresses the buildings file and caches map data for a week;
  the build targets ES2022 for top-level await
- Tests for decoding, factory clearance, machine reachability and tile
  placement

Imagery attribution: Esri, Maxar, Earthstar Geographics, and the GIS
User Community. Commercial use requires a suitable Esri licence.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

Caddyfile

@@ -2,7 +2,20 @@
 # or ":80" for plain HTTP behind another proxy or for a local test.
 {$SITE_ADDRESS::80} {
 	root * /srv
-	encode zstd gzip
+	# The defaults cover text and JSON; the binary buildings file compresses to about 60% too.
+	encode {
+		zstd
+		gzip
+		match {
+			# Repeated values for the same header are OR-ed.
+			header Content-Type text/*
+			header Content-Type application/json*
+			header Content-Type application/javascript*
+			header Content-Type application/manifest+json*
+			header Content-Type image/svg+xml*
+			header Content-Type application/octet-stream*
+		}
+	}
 
 	# Hashed build files never change; the page, service worker and manifest must always be revalidated
 	# so installed copies pick up new versions.
@@ -10,6 +23,9 @@
 	header @hashed Cache-Control "public, max-age=31536000, immutable"
 	@fresh path / /index.html /sw.js /manifest.webmanifest
 	header @fresh Cache-Control "no-cache"
+	# Map data and satellite tiles only change with a new map build.
+	@mapdata path /imagery/* /data/*
+	header @mapdata Cache-Control "public, max-age=604800"
 	@manifest path /manifest.webmanifest
 	header @manifest Content-Type "application/manifest+json"