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>

plugins/kyberforge/skills/plugin-create/SKILL.md

@@ -1,5 +1,5 @@
 ---
-name: create-plugin
+name: plugin-create
 description: >
   Use when the user wants to create a new plugin in the marketplace — scaffold the directory
   structure, generate plugin.json manifests for Claude Code and Copilot CLI, and register