refactor: Simplify marketplace name to 'nabledge'

Change marketplace name from 'nablarch-nabledge' to 'nabledge' for
simplicity. This makes the plugin installation command shorter:
- Before: /plugin install nabledge-6@nablarch-nabledge
- After: /plugin install nabledge-6@nabledge

Updated references in CHANGELOG and marketplace README.

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

Author: kiyotis

.claude/skills/nabledge-6/plugin/CHANGELOG.md

@@ -9,7 +9,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/).
 ### Changed
 - Migrated to Claude Code marketplace distribution structure
 - Plugin now distributed via marketplace catalog (nablarch/nabledge)
-- Users should install via: `/plugin marketplace add nablarch/nabledge` then `/plugin install nabledge-6@nablarch-nabledge`
+- Users should install via: `/plugin marketplace add nablarch/nabledge` then `/plugin install nabledge-6@nabledge`
 - Simplified license management: single LICENSE at repository root applies to entire marketplace
 
 ## [0.1] - 2026-02-12

.claude/skills/nabledge-6/plugin/marketplace-README.md

@@ -18,7 +18,7 @@ Nablarch 6 skill for AI-assisted development.
 /plugin marketplace add nablarch/nabledge
 
 # Install nabledge-6 plugin
-/plugin install nabledge-6@nablarch-nabledge
+/plugin install nabledge-6@nabledge
 ```
 
 **Usage**:

.claude/skills/nabledge-6/plugin/marketplace.json

@@ -1,5 +1,5 @@
 {
-  "name": "nablarch-nabledge",
+  "name": "nabledge",
   "description": "Nablarch skills for AI-assisted development",
   "owner": {
     "name": "Nablarch"