GraphRAG Studio — initial commit: multimodal RAG system with KG visualization

Full-stack application for document-to-knowledge-graph pipeline:
- Backend: FastAPI + LangGraph ReAct agent + DeepSeek + MinerU parsing
- Frontend: React 19 + Vite + D3.js + shadcn/ui
- Pipeline: MinerU parsing → LangExtract entity extraction → KG building

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

frontend/postcss.config.mjs

@@ -0,0 +1,15 @@
+/**
+ * PostCSS Configuration
+ *
+ * Tailwind CSS v4 (via @tailwindcss/vite) automatically sets up all required
+ * PostCSS plugins — you do NOT need to include `tailwindcss` or `autoprefixer` here.
+ *
+ * This file only exists for adding additional PostCSS plugins, if needed.
+ * For example:
+ *
+ * import postcssNested from 'postcss-nested'
+ * export default { plugins: [postcssNested()] }
+ *
+ * Otherwise, you can leave this file empty.
+ */
+export default {}