Phase 0: scaffold three-service backend (api/worker/frontend)

api/ (ElysiaJS+Bun WS gateway skeleton), worker/ (Rust, Redis dirty-chunk
stream consumer behind a swappable RenderBackend trait), frontend/
(ElysiaJS+Pug+Tailwind4+Alpine, one server-rendered page) — all three
verified running locally. docker-compose wires them up with postgres,
redis, minio (rendered tile/mesh object storage), and Caddy as reverse
proxy.

api/Dockerfile

@@ -0,0 +1,10 @@
+FROM oven/bun:1 AS base
+WORKDIR /app
+
+COPY package.json ./
+RUN bun install
+
+COPY . .
+
+EXPOSE 3000
+CMD ["bun", "run", "start"]