feat(docker): dev container so the app runs with only Docker

[WhiteMuush]

What

Add a development container so the app can run with only Docker installed, no Node or nvm on the host.

• Dockerfile: dev image (Node 22 + openssl for Prisma), deps installed in the image, runs next dev.
• .dockerignore: keeps node_modules/.next/.git out of the build context.
• compose.yml: adds an app service wired to db, source bind-mounted, node_modules kept in the container, migrations applied on start. DATABASE_URL is assembled at runtime to target the db service (never stored inline).

Usage

git pull
make env        # or make doctor (creates .env.local)
docker compose up

Verified

docker compose up brings up app + db, migrations applied, localhost:3000 responds 307.

Note

Building requires BuildKit/buildx. On a host without it, use DOCKER_BUILDKIT=0 docker compose build.