chore: initial project setup with backend, frontend, CI/CD, and documentation

Add complete NexaFabric project structure including:
- FastAPI backend with SQLAlchemy models, JWT auth, RBAC, audit logging, and provider interfaces
- React + TypeScript frontend with Vite, Tailwind CSS, TanStack Query, and Zustand
- Docker Compose configuration for PostgreSQL, Redis, API, worker, frontend, and nginx
- GitHub Actions and GitLab CI workflows for testing, linting, building, and security scanning
- Environment

frontend/tailwind.config.ts

@@ -0,0 +1,19 @@
+import type { Config } from "tailwindcss";
+
+export default {
+  darkMode: "class",
+  content: ["./index.html", "./src/**/*.{ts,tsx}"],
+  theme: {
+    extend: {
+      colors: {
+        canvas: "rgb(var(--color-canvas) / <alpha-value>)",
+        panel: "rgb(var(--color-panel) / <alpha-value>)",
+        border: "rgb(var(--color-border) / <alpha-value>)",
+        accent: "rgb(var(--color-accent) / <alpha-value>)",
+        danger: "rgb(var(--color-danger) / <alpha-value>)",
+      },
+    },
+  },
+  plugins: [],
+} satisfies Config;
+