feature: the entry point /shared exports the types and constants a server and its web application share.

package.json

@@ -1,6 +1,6 @@
 {
   "name": "@koszewscy/sk-react-toolkit",
-  "version": "0.4.0",
+  "version": "0.5.0",
   "description": "Shared code of the React and Fastify web applications: web components, server helpers and the Vite font plugin.",
   "private": true,
   "type": "module",
@@ -13,6 +13,7 @@
   },
   "exports": {
     "./server": "./server/index.ts",
+    "./shared": "./shared/index.ts",
     "./web": "./web/index.ts",
     "./vite": "./vite/index.ts"
   },