feat: initial release of pengzhan.dev personal editorial blog platform

- Editorial web platform built with Node.js, Express, EJS, and Vanilla CSS
- Markdown content engine with YAML frontmatter, bilingual variants, and hot-reload watcher
- Unified SQLite with FTS5 search indexing, query logging, and schema filters
- Centered editorial post layout with margin-docked left TOC and mobile bottom sheet
- WordPress-grade comment system with moderation dashboard and bulk operations under /guanli
- Complete SEO suite (JSON-LD structured data, RSS/Atom feeds, XML sitemap, robots.txt)
- CI/CD workflows for linting, security audits (Gitleaks), automated tests, and Docker releases

server/middleware/error-handler.js

@@ -0,0 +1,23 @@
+function notFoundHandler(req, res, next) {
+  res.status(404);
+  res.render('pages/error', {
+    title: '404 - Page Not Found',
+    errorCode: 404,
+    errorMessage: "The page you are looking for doesn't exist or has moved."
+  });
+}
+
+function serverErrorHandler(err, req, res, next) {
+  console.error('[ServerError]', err);
+  res.status(500);
+  res.render('pages/error', {
+    title: '500 - Server Error',
+    errorCode: 500,
+    errorMessage: "An unexpected error occurred."
+  });
+}
+
+module.exports = {
+  notFoundHandler,
+  serverErrorHandler
+};