chore: restructure into monorepo and add open-source documentation

- Rename helix-server -> server and helix-web -> web
- Remove helix-api (bruno collection and docs site)
- Merge per-module .gitignore files into the root .gitignore
- Add README, AGENTS, CONTRIBUTING and MIT LICENCE
- Add full-stack docker-compose (postgres, redis, server, web via Caddy)
  with web Dockerfile, Caddyfile and Compose server config
- Keep the Gradle wrapper jar tracked after the .gitignore merge
- Copy gradle.properties into the server Docker build image

web/src/components/protected-route/index.tsx

@@ -0,0 +1,22 @@
+import { Navigate, Outlet, useLocation } from "react-router"
+import { useAppSelector } from "@/store"
+import DashboardLayout from "@/layouts/dashboard-layout"
+
+/**
+ * 需要身份验证的前置组件
+ * @constructor
+ */
+export default function ProtectedRoute() {
+  const isAuthenticated = useAppSelector((state) => state.auth.isAuthenticated)
+  const location = useLocation()
+
+  if (!isAuthenticated) {
+    return <Navigate to="/login" state={{ from: location }} replace />
+  }
+
+  return (
+    <DashboardLayout >
+      <Outlet />
+    </DashboardLayout>
+  )
+}