Add post: Replacing RDPGuard With IPBan (EN + ZH, og+banner)

Case study of migrating from paid RDPGuard 7.8.7 to open-source IPBan
4.1.0, covering the three undocumented traps: the uninstaller that would
have silently unbanned 12 active attackers, the non-existent
--install-service flag in v4.1.0, and ExpireTime vs BanTime.

Also fixes an og-gen defect: the tag chip hardcoded KIND='DevOps', so
every non-devops post carried a wrong label (e.g. "case-studies · DevOps"
on the STT card). KIND now derives from the post category, and all 29
existing OG images are regenerated with correct badges.

scripts/og-gen/template.html

@@ -78,7 +78,7 @@
     <div class="brand">Mr Hoelee <span class="domain">· blog.hoelee.com</span></div>
   </div>
 
-  <div class="tag"><span class="dot"></span>{{CATEGORY}} · {{KIND}}</div>
+  <div class="tag"><span class="dot"></span>{{CATEGORY}}</div>
 
   <div class="title">{{TITLE_HTML}}</div>