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

views/pages/search.ejs

@@ -21,19 +21,25 @@
     </form>
 
     <!-- Sleek Discovery & Recommended Searches -->
-    <div class="search-discovery-pills" style="margin-top: 1.25rem;">
+    <div class="search-discovery-pills" style="margin-top: 1.5rem;">
+      <% if (recommended.customPills && recommended.customPills.length > 0) { %>
+        <div style="font-size: 0.8rem; text-transform: uppercase; letter-spacing: 0.05em; color: var(--color-text-muted); margin-bottom: 0.6rem; font-weight: 600;">🔥 Trending Searches</div>
+        <div class="search-pills-grid" style="margin-bottom: 1.25rem;">
+          <% recommended.customPills.forEach(pill => { %>
+            <button type="button" class="pill search-pill-btn" data-query="<%= pill.query %>">
+              <%= pill.label %>
+            </button>
+          <% }) %>
+        </div>
+      <% } %>
+
+      <div style="font-size: 0.8rem; text-transform: uppercase; letter-spacing: 0.05em; color: var(--color-text-muted); margin-bottom: 0.6rem; font-weight: 600;">🏷️ Browse Topics</div>
       <div class="search-pills-grid">
         <% (recommended.dynamicPills || []).forEach(pill => { %>
           <button type="button" class="pill search-pill-btn" data-query="<%= pill.query %>">
             <%= pill.label %>
           </button>
         <% }) %>
-
-        <% (recommended.customPills || []).forEach(pill => { %>
-          <button type="button" class="pill search-pill-btn" data-query="<%= pill.query %>">
-            <%= pill.label %>
-          </button>
-        <% }) %>
       </div>
     </div>
   </div>