build: add esbuild scaffolding and Docker build-assets target

package.json with esbuild ^0.21 and npm dependencies (maplibre-gl,
photoswipe, scrollama, fontsource). Placeholder src files and
compiled outputs committed. node_modules gitignored.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Vgmzx8VTTTmCskSpQtsLTr

themes/intotheeast/package.json

@@ -0,0 +1,17 @@
+{
+  "private": true,
+  "scripts": {
+    "build": "esbuild js/src/main.js --bundle --minify --format=iife --outfile=js/main.js --loader:.woff2=file --loader:.woff=file --asset-names=../fonts/[name] && esbuild js/src/map.js --bundle --minify --format=iife --outfile=js/map.js && mkdir -p css-compiled fonts && { mv js/main.css css-compiled/main.css 2>/dev/null || true; } && { mv js/map.css css-compiled/map.css 2>/dev/null || true; }"
+  },
+  "dependencies": {
+    "@fontsource-variable/dm-sans": "latest",
+    "@fontsource/dm-serif-display": "latest",
+    "@mapbox/togeojson": "^0.16.2",
+    "maplibre-gl": "^4",
+    "photoswipe": "^5",
+    "scrollama": "^3"
+  },
+  "devDependencies": {
+    "esbuild": "^0.21"
+  }
+}