feat: prepare nobat724_front for deployment on Liara platform

- Added Node.js engine requirement in package.json to ensure compatibility.
- Created liara-deploy.md for deployment instructions and environment setup.
- Added example environment variables in .env.liara.example for clarity.
- Introduced .liaraignore to exclude unnecessary files from deployment.
- Created liara.json for Liara configuration, including health check settings.
- Removed redundant next.config.mjs file to prevent configuration conflicts.

.liaraignore

@@ -0,0 +1,26 @@
+# Liara upload excludes. Liara runs `npm install` + `npm run build` itself, so
+# local build artifacts and deps are not uploaded.
+.git
+.github
+node_modules
+.next
+
+# Docker / Coolify artifacts — unused on the Next.js platform.
+Dockerfile
+.dockerignore
+docker-compose.yml
+
+# Local env & secrets — set these in the Liara console (build-time NEXT_PUBLIC_*).
+.env
+.env.local
+.env.*.local
+
+# Tests, editor, runtime noise.
+tests
+__tests__
+vitest.config.*
+coverage
+.vscode
+.idea
+*.log
+.DS_Store