feat: add node help system and registry for extensible node types

- Implemented a help system for different node types (config, render, variable, function) with detailed usage instructions.
- Created a node registry to manage node types, including registration, retrieval, and validation of connections between nodes.
- Defined central node and edge types for the application to streamline state management.
- Added Nunjucks autocomplete functionality to enhance user experience in template editing.
- Developed a syntax highlighting parser for PlantUML and Nunjucks within the CodeMirror editor.
- Registered built-in node types at application startup, including their default configurations and help entries.
- Introduced a theme context provider to manage light/dark mode preferences across the application.
- Created utility functions for class name management using clsx and tailwind-merge.
- Set up Tailwind CSS for styling with custom themes and responsive design.
- Configured Vite for development with proxy settings for backend API calls and Kroki diagram service.

docker-compose.yml

@@ -0,0 +1,40 @@
+# Zui: frontend (Nginx) + backend (Express). No DB.
+# Usage: docker compose up --build
+# Dev with hot reload: use frontend/Dockerfile.dev and mount ./frontend, or run npm run dev locally.
+
+services:
+  frontend:
+    build:
+      context: ./frontend
+      dockerfile: Dockerfile
+    ports:
+      - "3000:80"
+    depends_on:
+      backend:
+        condition: service_healthy
+    environment:
+      - VITE_API_URL=http://localhost:8080
+    networks:
+      - app
+
+  backend:
+    build:
+      context: ./backend
+      dockerfile: Dockerfile
+    ports:
+      - "8080:8080"
+    environment:
+      - PORT=8080
+      - CORS_ORIGIN=http://localhost:3000
+    healthcheck:
+      test: ["CMD", "node", "-e", "require('http').get('http://localhost:8080/health', (r) => process.exit(r.statusCode === 200 ? 0 : 1))"]
+      interval: 30s
+      timeout: 3s
+      start_period: 5s
+      retries: 3
+    networks:
+      - app
+
+networks:
+  app:
+    driver: bridge