refactor(fonts): Google Fonts 改为本地字体文件

- 移除 next/font/google 依赖，改用 next/font/local 加载本地 woff2 字体
- 新增 Geist Sans/Mono、Noto Sans SC、Ma Shan Zheng 本地字体文件
- 解决国内网络环境下 fonts.gstatic.com 不可达导致构建失败的问题
- 移除未使用的 image-filters.ts (WASM 模块声明导致 TS 编译错误)

src/app/layout.tsx

@@ -1,5 +1,4 @@
 import type { Metadata, Viewport } from "next";
-import { Geist, Geist_Mono, Noto_Sans_SC, Ma_Shan_Zheng } from "next/font/google";
 import localFont from "next/font/local";
 import "./globals.css";
 import { Suspense } from "react";
@@ -17,32 +16,40 @@ import { BackToTop } from "@/components/ui/back-to-top";
 
 const GA_MEASUREMENT_ID = process.env.NEXT_PUBLIC_GA_MEASUREMENT_ID || '';
 
-const geistSans = Geist({
+const geistSans = localFont({
+  src: [
+    { path: "./fonts/geist-sans/geist-sans-latin-400-normal.woff2", weight: "400" },
+    { path: "./fonts/geist-sans/geist-sans-latin-700-normal.woff2", weight: "700" },
+  ],
   variable: "--font-geist-sans",
-  subsets: ["latin"],
   display: "swap",
   preload: false,
 });
 
-const geistMono = Geist_Mono({
+const geistMono = localFont({
+  src: [
+    { path: "./fonts/geist-mono/geist-mono-latin-400-normal.woff2", weight: "400" },
+    { path: "./fonts/geist-mono/geist-mono-latin-700-normal.woff2", weight: "700" },
+  ],
   variable: "--font-geist-mono",
-  subsets: ["latin"],
   display: "swap",
   preload: false,
 });
 
-const notoSansSC = Noto_Sans_SC({
-  weight: ["400", "500", "700"],
+const notoSansSC = localFont({
+  src: [
+    { path: "./fonts/noto-sans-sc/noto-sans-sc-chinese-simplified-400-normal.woff2", weight: "400" },
+    { path: "./fonts/noto-sans-sc/noto-sans-sc-chinese-simplified-500-normal.woff2", weight: "500" },
+    { path: "./fonts/noto-sans-sc/noto-sans-sc-chinese-simplified-700-normal.woff2", weight: "700" },
+  ],
   variable: "--font-noto-sans-sc",
-  subsets: ["latin"],
   display: "swap",
   preload: true,
 });
 
-const maShanZheng = Ma_Shan_Zheng({
-  weight: "400",
+const maShanZheng = localFont({
+  src: "./fonts/ma-shan-zheng/ma-shan-zheng-chinese-simplified-400-normal.woff2",
   variable: "--font-ma-shan-zheng",
-  subsets: ["latin"],
   display: "swap",
   preload: true,
 });