Add Dockerfile, docker-compose.yml, and coolify.json for deployment

SPA pattern: node build → nginx serve on port 3000, exposed via HOST_PORT.
Deploys to box-repoapps as spike-breakdown on port 2011, domain spikes.dotrepo.com.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

docker-compose.yml

@@ -0,0 +1,13 @@
+services:
+  spike-breakdown:
+    build: .
+    image: spike-breakdown:latest
+    container_name: spike-breakdown
+    restart: unless-stopped
+    ports:
+      - "${HOST_PORT:-3000}:3000"
+    healthcheck:
+      test: ["CMD", "wget", "-qO-", "http://localhost:3000/"]
+      interval: 60s
+      timeout: 10s
+      retries: 3