fix: center title, add v0.4.0 release notes

- Center H1 title in all language READMEs
- Add detailed v0.4.0 release notes to RELEASES.md and CHANGELOG.md
- 175 new skills breakdown by category

skills/calendar/.clawhub/origin.json

@@ -1,7 +0,0 @@
-{
-  "version": 1,
-  "registry": "https://clawhub.ai",
-  "slug": "calendar",
-  "installedVersion": "1.0.0",
-  "installedAt": 1773229764192
-}

skills/calendar/_meta.json

@@ -1,6 +0,0 @@
-{
-  "ownerId": "kn72dx5ngyt147nvk6j9bgj42n80ra91",
-  "slug": "calendar",
-  "version": "1.0.0",
-  "publishedAt": 1771427803561
-}