fix(blog): switch giscus category to General

GitHub's default Announcements discussion category is maintainer-only
by design, so logged-in users without admin rights can't post via
giscus — they got 'Unable to create discussion' even though the
giscus-app was installed with Read+Write permissions.

General is open to all repo visitors who are logged into GitHub.

Discussion category id confirmed via GitHub GraphQL API:
  Announcements = DIC_kwDOFxYtfs4DEf3i (maintainer-only, rejected)
  General       = DIC_kwDOFxYtfs4DEf3j (open to all)

Author: lzm

hugo.yaml

@@ -75,8 +75,8 @@ params:
   giscus:
     repo: "LiMingCoding/LiMingCoding.github.io"
     repoId: "387329406"
-    category: "announcements"
-    categoryId: "DIC_kwDOFxYtfs4DEf3i"
+    category: "general"
+    categoryId: "DIC_kwDOFxYtfs4DEf3j"
     mapping: "pathname"
     strict: "0"
     reactionsEnabled: "1"