Initial project structure for Wrenn Sandbox

Set up directory layout, Makefiles, go.mod files, docker-compose,
and empty placeholder files for all packages.

deploy/docker-compose.dev.yml

@@ -0,0 +1,28 @@
+services:
+  postgres:
+    image: postgres:16-alpine
+    environment:
+      POSTGRES_USER: wrenn
+      POSTGRES_PASSWORD: wrenn
+      POSTGRES_DB: wrenn
+    ports:
+      - "5432:5432"
+    volumes:
+      - pgdata:/var/lib/postgresql/data
+
+  prometheus:
+    image: prom/prometheus:latest
+    ports:
+      - "9090:9090"
+    volumes:
+      - ./deploy/prometheus.yml:/etc/prometheus/prometheus.yml
+
+  grafana:
+    image: grafana/grafana:latest
+    ports:
+      - "3001:3000"
+    environment:
+      GF_SECURITY_ADMIN_PASSWORD: admin
+
+volumes:
+  pgdata: