sx-http: Docker compose overlay + auto-detect component dir

docker-compose.dev-sx-native.yml overrides entrypoint to run OCaml
HTTP server inside Docker container (Caddy on externalnet can reach it).

Auto-detect sx component directory: checks /app/sx (Docker) first,
falls back to /project/sx/sx (dev). SX_COMPONENTS_DIR env override.

Live on sx.rose-ash.com via Caddy → Docker → OCaml HTTP server.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

docker-compose.dev-sx-native.yml

@@ -0,0 +1,14 @@
+# Native OCaml HTTP server for sx_docs — no Python, no Quart
+# Overrides dev-sx.yml entrypoint to use sx_server --http
+#
+# Usage:
+#   docker compose -p sx-dev -f docker-compose.dev-sx.yml -f docker-compose.dev-sx-native.yml up
+
+services:
+  sx_docs:
+    entrypoint: ["/app/bin/sx_server", "--http", "8000"]
+    environment:
+      SX_PROJECT_DIR: /app
+      SX_SPEC_DIR: /app/spec
+      SX_LIB_DIR: /app/lib
+      SX_WEB_DIR: /app/web