docs(engineering): add project audit report and improvement plan

This commit introduces a comprehensive engineering audit report for the Tootaio Studio project. The report is structured into documents covering architecture, code quality, performance, security, CI/CD, and
observability. It also includes a phased improvement roadmap and a set of `.patch` files to apply immediate fixes for content schemas, package scripts, and CI configuration.

docs/20251106/patches/0004-nuxt-route-rules.patch

@@ -0,0 +1,50 @@
+diff --git a/nuxt.config.ts b/nuxt.config.ts
+--- a/nuxt.config.ts
++++ b/nuxt.config.ts
+@@
+ export default defineNuxtConfig({
+   compatibilityDate: "2025-07-15",
+   devtools: { enabled: true },
+   modules: [
+     "@nuxt/content",
+     "@nuxt/ui",
+     "@nuxt/eslint",
+     "@nuxtjs/i18n",
+     "@nuxtjs/seo",
+   ],
+   css: ["@/assets/css/main.css"],
+   app: {
+     head: {
+       titleTemplate: "%s - Tootaio Studio",
+       meta: [
+         { name: "viewport", content: "width=device-width, initial-scale=1" },
+         { charset: "utf-8" },
+       ],
+     },
+   },
+@@
+   seo: {
+     meta: {
+       title: DEFAULT_SEO.title,
+       description: DEFAULT_SEO.description,
+       keywords: DEFAULT_SEO.keywords,
+       ogTitle: DEFAULT_SEO.title,
+       ogDescription: DEFAULT_SEO.description,
+       ogImage: DEFAULT_SEO.image,
+       ogUrl: DEFAULT_SEO.url,
+       twitterCard: "summary_large_image",
+       twitterTitle: DEFAULT_SEO.title,
+       twitterDescription: DEFAULT_SEO.description,
+       twitterImage: DEFAULT_SEO.image,
+     },
+   },
+   site: {
+     url: "https://tootaio.com",
+   },
++  routeRules: {
++    "/": { prerender: true, swr: 3600 },
++    "/_nuxt/**": {
++      headers: { "cache-control": "public, max-age=31536000, immutable" },
++    },
++  },
+ });