🚀 Chore(ci/cd): improve the joint construction and deployment of Demo and Test content

- Demo: https://demo.fixit.lruihao.cn/
- Test: https://demo.fixit.lruihao.cn/test/

test/content/posts/_index.md

@@ -0,0 +1,4 @@
+---
+title: All Tests
+titleIcon: fa-solid fa-flask
+---

test/content/posts/exact-color-match-test.md

@@ -3,6 +3,10 @@ title: Exact Color Match Test
 date: 2025-08-17T17:20:00+08:00
 collections:
   - Tests
+categories:
+  - Markdown
+tags:
+  - Color Preview
 ---
 
 ## 📝 Syntax