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.

.env.liara.example

@@ -0,0 +1,14 @@
+# ============================================================
+# Liara env vars — nobat724_front (Next.js platform)
+# ------------------------------------------------------------
+# NEXT_PUBLIC_* are baked into the client bundle AT BUILD TIME, so set them in the
+# Liara console BEFORE the first deploy; changing them later needs a REDEPLOY
+# (not just a restart). Set via console (Environment tab) or:
+#   liara env:set KEY=VALUE --app nobat724
+# ============================================================
+
+# Backend API base — all /api/v1/* and /oauth/token calls hit this origin.
+NEXT_PUBLIC_API_URL=https://clinic-pro.ir
+
+# FALSE → allow search-engine indexing (production). TRUE → noindex + block crawlers (staging).
+DEV_MODE=FALSE