feat(admin): add ephemeral staging DB, read-only posts overview, and dynamic search

- Implement ephemeral staging mode (APP_ENV=staging) to isolate test/dev DB writes in /tmp
- Add read-only posts management dashboard under /guanli/posts with live links and comment counters
- Add hot re-indexing endpoint (/guanli/reindex) to refresh Markdown without restarting server
- Replace static recommended search config with dynamic frequency-based trending searches
- Remove early scaffold mockup file (dropbox/zh.md) and clean legacy mock test queries
- Add native Makefile with dev, dev-persistent, test, lint, and docker targets
- Update test suite and documentation for development workflows

server/routes/admin.js

@@ -102,6 +102,57 @@ router.get('/guanli/logout', (req, res) => {
 
 const dbService = require('../services/db');
 
+// 0. Posts Read-Only Overview Dashboard
+router.get('/guanli/posts', requireAdminAuth, (req, res) => {
+  const q = (req.query.q || '').trim().toLowerCase();
+  const activeCategory = (req.query.category || '').trim();
+
+  const allPosts = contentService.getAllPosts();
+  let filteredPosts = allPosts;
+
+  if (activeCategory) {
+    filteredPosts = filteredPosts.filter(p => (p.category || '').toLowerCase() === activeCategory.toLowerCase());
+  }
+
+  if (q) {
+    filteredPosts = filteredPosts.filter(p => 
+      (p.title || '').toLowerCase().includes(q) ||
+      (p.slug || '').toLowerCase().includes(q) ||
+      (p.tags || []).some(t => t.toLowerCase().includes(q))
+    );
+  }
+
+  const taxonomy = contentService.getTaxonomy();
+  const commentStats = dbService.getPostCommentStats();
+  const stats = dbService.getAdminStats();
+
+  res.render('pages/admin-posts', {
+    title: 'Posts Overview - Site Administration',
+    posts: allPosts,
+    filteredPosts,
+    categories: taxonomy.categories,
+    activeCategory,
+    q: req.query.q || '',
+    commentStats,
+    stats
+  });
+});
+
+// Hot Content Re-index & Cache Flush endpoint
+router.post('/guanli/reindex', requireAdminAuth, (req, res) => {
+  try {
+    const { CONTENT_DIR } = require('../config');
+    contentService.init(CONTENT_DIR);
+    pageCache.clear();
+    const totalPosts = contentService.getAllPosts().length;
+    const totalPages = contentService.pagesBySlug.size;
+    res.json({ success: true, totalPosts, totalPages });
+  } catch (err) {
+    console.error('[Admin] Hot re-index failed:', err);
+    res.status(500).json({ success: false, error: err.message });
+  }
+});
+
 // 1. Comment Moderation Dashboard
 router.get('/guanli/comments', requireAdminAuth, (req, res) => {
   const status = req.query.status || 'all';