Add Docker Compose setup with persistent volume

Improve the production Dockerfile (healthcheck, entrypoint bootstrap
user, pruned deps) and add docker-compose.yml plus .dockerignore for
one-command deploy with a named SQLite volume.

.dockerignore

@@ -0,0 +1,15 @@
+node_modules
+.next
+.git
+data
+*.db
+*.db-*
+.env
+.env.*
+!.env.example
+coverage
+tests
+.github
+.cursor
+**/*.md
+!README.md