feat(train): the instance's own map tiles, drawn by Train's style (ADR 0030, D50)

Protomaps' basemap cut for Europe and served by pmtiles beside Train's server
(compose.maps.yaml), drawn by Train's own style, light and dark, which the
server serves. Only people signed in get tiles: map.source hands a key that
Caddy has the server check before each tile; nothing logs a tile.

Also fixes .dockerignore, which left apps/train/ out of the build context, so
Train's server's and BRouter's images couldn't have been built.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Signed-off-by: Tizian 「ティツィアーン」 <raisondetredev@pm.me>

deploy/redeploy.sh

@@ -71,6 +71,10 @@ main() {
   if [ -n "$train" ]; then
     docker compose build -q train-server brouter
   fi
+  # Train's own map, where .env switches it on (compose.maps.yaml).
+  if docker compose config --services | grep -qx map-tiles; then
+    docker compose build -q map-tiles
+  fi
   dump halkyon_learn
   if [ -n "$train" ]; then
     dump halkyon_train