build: docker compose (app + postgres) with healthchecks and .env

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01BwxdSt4reTm7Dj1oxRvpP3

Makefile

@@ -14,3 +14,16 @@ web:
 
 .PHONY: build-all
 build-all: web build
+
+.PHONY: docker-build docker-up docker-down docker-logs
+docker-build:
+	docker build -t dns-autoresolver:local .
+
+docker-up:
+	docker compose up -d --build
+
+docker-down:
+	docker compose down
+
+docker-logs:
+	docker compose logs -f app