Add obsidian-official-cli skill from ClawhHub

Obsidian CLI (v1.12+) reference skill for all agents — covers file ops,
search, tasks, templates, plugins, sync, and dev tools.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

skills/obsidian-official-cli/_meta.json

@@ -0,0 +1,6 @@
+{
+  "ownerId": "kn7etsekxfxt0s4sv9h32j0vd980yb5y",
+  "slug": "obsidian-official-cli",
+  "version": "1.0.0",
+  "publishedAt": 1770778403903
+}