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/services/db.js

@@ -1,11 +1,13 @@
 const fs = require('fs');
 const path = require('path');
+const os = require('os');
 const { DatabaseSync } = require('node:sqlite');
 
 class DatabaseService {
   constructor() {
     this.db = null;
     this.dbPath = null;
+    this.isEphemeral = false;
   }
 
   init(contentDir) {
@@ -14,8 +16,43 @@ class DatabaseService {
       fs.mkdirSync(dataDir, { recursive: true });
     }
 
-    this.dbPath = path.join(dataDir, 'site.db');
-    this.db = new DatabaseSync(this.dbPath);
+    const isStaging = process.env.NODE_ENV === 'test' || process.env.APP_ENV === 'staging' || process.env.DB_EPHEMERAL === 'true';
+    const prodDbPath = path.join(dataDir, 'site.db');
+
+    if (isStaging) {
+      this.isEphemeral = true;
+      const ephemeralName = `site.staging-${process.pid}-${Date.now()}.db`;
+      this.dbPath = path.join(os.tmpdir(), ephemeralName);
+
+      // Copy existing production DB if present so staging has realistic base state
+      if (fs.existsSync(prodDbPath)) {
+        try {
+          fs.copyFileSync(prodDbPath, this.dbPath);
+        } catch (_) {}
+      }
+
+      // Automatically clean up ephemeral DB on process exit
+      const cleanup = () => {
+        try {
+          if (this.db) {
+            this.db.close();
+            this.db = null;
+          }
+          if (fs.existsSync(this.dbPath)) {
+            fs.unlinkSync(this.dbPath);
+          }
+        } catch (_) {}
+      };
+      process.once('exit', cleanup);
+      process.once('SIGINT', () => { cleanup(); process.exit(0); });
+      process.once('SIGTERM', () => { cleanup(); process.exit(0); });
+
+      this.db = new DatabaseSync(this.dbPath);
+      console.log(`[DB] Ephemeral Staging SQLite database initialized at ${this.dbPath}`);
+    } else {
+      this.dbPath = prodDbPath;
+      this.db = new DatabaseSync(this.dbPath);
+    }
 
     // Initialize unified tables
     this.db.exec(`
@@ -204,6 +241,65 @@ class DatabaseService {
     }
   }
 
+  // Aggregate genuine popular searches by frequency where result_count > 0
+  getTopSearchQueries(limit = 6) {
+    if (!this.db) return [];
+    try {
+      const stmt = this.db.prepare(`
+        SELECT query, COUNT(*) as frequency
+        FROM search_logs
+        WHERE result_count > 0 AND length(trim(query)) >= 2
+        GROUP BY lower(trim(query))
+        ORDER BY frequency DESC
+        LIMIT ?
+      `);
+      return stmt.all(limit).map(r => ({
+        label: r.query,
+        query: r.query,
+        frequency: r.frequency
+      }));
+    } catch (err) {
+      console.error('[DB] Error fetching top search queries:', err);
+      return [];
+    }
+  }
+
+  // Get total & pending comment counts per post slug
+  getPostCommentStats() {
+    if (!this.db) return new Map();
+    try {
+      const stmt = this.db.prepare(`
+        SELECT post_slug,
+               COUNT(*) as total,
+               SUM(CASE WHEN approved = 0 THEN 1 ELSE 0 END) as pending
+        FROM comments
+        GROUP BY post_slug
+      `);
+      const rows = stmt.all();
+      const map = new Map();
+      for (const row of rows) {
+        map.set(row.post_slug, {
+          total: row.total || 0,
+          pending: row.pending || 0
+        });
+      }
+      return map;
+    } catch (err) {
+      console.error('[DB] Error fetching post comment stats:', err);
+      return new Map();
+    }
+  }
+
+  cleanTestSearchData() {
+    if (!this.db) return;
+    try {
+      this.db.exec(`
+        DELETE FROM search_logs WHERE query LIKE '%container image%' OR query LIKE '%tag:k8s "container image"%';
+        DELETE FROM search_recommendations WHERE query LIKE '%container image%';
+      `);
+    } catch (_) {}
+  }
+
   // --- Comments & WordPress-Grade Moderation Workflow ---
   isAuthorWhitelisted(email) {
     if (!this.db || !email) return false;