feat: add about page with versions, changelog, and how-to-play

- New GET /about API endpoint caches Gitea releases for 5 minutes
- AboutPanel displays client version (via Vite define), API version, collapsible changelog, and How to Play guide
- GiteaRelease and AboutResponse types added to shared package

apps/web/vite.config.ts

@@ -1,7 +1,15 @@
+import { readFileSync } from "node:fs";
 import react from "@vitejs/plugin-react";
 import { defineConfig } from "vite";
 
+const { version: WEB_VERSION } = JSON.parse(
+  readFileSync("./package.json", "utf-8"),
+) as { version: string };
+
 export default defineConfig({
+  define: {
+    __WEB_VERSION__: JSON.stringify(WEB_VERSION),
+  },
   plugins: [react()],
   server: {
     port: 5173,