refactor(fonts): move font definitions to a dedicated fonts module

src/app/layout.tsx

@@ -1,54 +1,10 @@
 import type { Metadata } from "next";
-import { Geist, Geist_Mono } from "next/font/google";
-import localFont from "next/font/local";
 import { SessionProvider } from "@/providers/session-provider";
+import { geistSans, geistMono, athelas } from "@/lib/fonts";
 import "./globals.css";
 
 import { RootProviders } from "@/providers/root-providers";
 
-const geistSans = Geist({
-  variable: "--font-geist-sans",
-  subsets: ["latin"],
-});
-
-const geistMono = Geist_Mono({
-  variable: "--font-geist-mono",
-  subsets: ["latin"],
-});
-
-/**
- * Athelas 字体加载
- * 原始资源：/Users/chase/Documents/cozsweet/fonts/Athelas-*.ttf
- * 放置位置：/public/fonts/Athelas-*.ttf
- *
- * 路径计算（`next/font/local` 要求相对路径从调用文件出发）：
- *   src/app/layout.tsx → ../../public/fonts/...
- *
- * 通过 `next/font/local` 自动 preload、压缩、inline。
- * 输出 CSS 变量 `--font-athelas`，由 `globals.css` 桥接到 Tailwind `font-athelas`。
- */
-const athelas = localFont({
-  src: [
-    {
-      path: "../../public/fonts/Athelas-Regular.ttf",
-      weight: "400",
-      style: "normal",
-    },
-    {
-      path: "../../public/fonts/Athelas-Bold.ttf",
-      weight: "700",
-      style: "normal",
-    },
-    {
-      path: "../../public/fonts/Athelas-BoldItalic.ttf",
-      weight: "700",
-      style: "italic",
-    },
-  ],
-  variable: "--font-athelas",
-  display: "swap",
-});
-
 export const metadata: Metadata = {
   title: "cozsweet",
   description: "cozsweet frontend (Next.js)",

src/lib/fonts.ts

@@ -0,0 +1,56 @@
+import { Geist, Geist_Mono } from "next/font/google";
+import localFont from "next/font/local";
+
+/**
+ * 全局字体配置（仅供服务端组件使用，例如 `src/app/layout.tsx`）。
+ *
+ * - `next/font/google` 与 `next/font/local` 在构建期完成 self-host、preload、
+ *   subset、inline，浏览器不会向 Google 发送请求，也不会产生 layout shift。
+ * - 产出的 CSS 变量由 `globals.css` 桥接到 Tailwind（如 `font-sans`、`font-athelas`）。
+ *
+ * 注意：本文件**不**通过 `src/lib/index.ts` 桶导出，避免被误打进客户端 bundle。
+ *       引用方式：`import { geistSans, geistMono, athelas } from "@/lib/fonts";`
+ */
+
+const geistSans = Geist({
+  variable: "--font-geist-sans",
+  subsets: ["latin"],
+});
+
+const geistMono = Geist_Mono({
+  variable: "--font-geist-mono",
+  subsets: ["latin"],
+});
+
+/**
+ * Athelas 本地字体。
+ *
+ * 原始资源：/Users/chase/Documents/cozsweet/fonts/Athelas-*.ttf
+ * 放置位置：/public/fonts/Athelas-*.ttf
+ *
+ * 路径计算（`next/font/local` 要求相对路径从**调用文件**出发）：
+ *   src/lib/fonts.ts → ../../public/fonts/...
+ */
+const athelas = localFont({
+  src: [
+    {
+      path: "../../public/fonts/Athelas-Regular.ttf",
+      weight: "400",
+      style: "normal",
+    },
+    {
+      path: "../../public/fonts/Athelas-Bold.ttf",
+      weight: "700",
+      style: "normal",
+    },
+    {
+      path: "../../public/fonts/Athelas-BoldItalic.ttf",
+      weight: "700",
+      style: "italic",
+    },
+  ],
+  variable: "--font-athelas",
+  display: "swap",
+});
+
+export { geistSans, geistMono, athelas };