chore: rename create-plugin skill to plugin-create, add project settings

Renames plugins/kyberforge/skills/create-plugin/ to plugin-create/ to match
the directory-based skill name Claude Code uses for slash commands. Adds
.claude/settings.json with kyberforge plugin enabled. Gitignores
.claude/settings.local.json (machine-local MCP permissions).

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

.claude/settings.json

@@ -0,0 +1,5 @@
+{
+  "enabledPlugins": {
+    "kyberforge@holocron": true
+  }
+}