feat(06-01): add Docker configuration for production deployment

- Create Dockerfile with multi-stage build using node:22-alpine
- Run as non-root 'nodejs' user for security
- Add HEALTHCHECK for container orchestration
- Create docker-compose.yml with taskplaner_data named volume
- Add .dockerignore to optimize build context

.dockerignore

@@ -0,0 +1,10 @@
+node_modules
+build
+.svelte-kit
+data
+.git
+.gitignore
+.env*
+*.md
+.planning
+.vscode