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.

Caddyfile

@@ -0,0 +1,20 @@
+# Reverse proxy: WS/API traffic to `api`, everything else to `frontend`.
+# Point CADDY_DOMAIN at a real hostname (and remove `auto_https off` + the `:80` binding
+# below) once this is deployed somewhere with a resolvable domain for automatic TLS.
+{
+	auto_https off
+}
+
+:80 {
+	handle /ws* {
+		reverse_proxy api:3000
+	}
+
+	handle /api/* {
+		reverse_proxy api:3000
+	}
+
+	handle {
+		reverse_proxy frontend:3001
+	}
+}