refactor: Move marketplace files to .claude/marketplace directory

Address PR review feedback:
1. Move marketplace files from .claude/skills/nabledge-6/plugin/ to .claude/marketplace/
   - marketplace.json → .claude/marketplace/.claude-plugin/marketplace.json
   - marketplace-README.md → .claude/marketplace/README.md
   - LICENSE (copy) → .claude/marketplace/LICENSE

2. Add command explanations to plugin README:
   - /nabledge-6: Basic skill invocation for interactive questions
   - /nabledge-6 "query": Knowledge search with specific questions
   - /nabledge-6 code-analysis: Analyze project code from Nablarch perspective

3. Update transform script and GitHub Action to use new marketplace location

This provides clearer separation between marketplace metadata and plugin files.

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

Author: kiyotis

…kills/nabledge-6/plugin/marketplace.json …ketplace/.claude-plugin/marketplace.json.claude/skills/nabledge-6/plugin/marketplace.json renamed to .claude/marketplace/.claude-plugin/marketplace.json .claude/skills/nabledge-6/plugin/marketplace.json renamed to .claude/marketplace/.claude-plugin/marketplace.json

@@ -0,0 +1,16 @@
+Apache License
+Version 2.0, January 2004
+
+Copyright 2026 Nablarch
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.

.claude/marketplace/LICENSE

@@ -33,18 +33,24 @@ curl -sSL https://raw.githubusercontent.com/nablarch/nabledge/main/.claude/skill
 /nabledge-6
 ```
 
+スキルを起動し、対話的にNablarchに関する質問や、コード分析を行うことができます。
+
 ### 知識検索
 
 ```bash
 /nabledge-6 "バッチ処理の実装方法を教えて"
 ```
 
+Nablarch 6のドキュメントやベストプラクティスから知識を検索し、回答を得ることができます。質問は日本語でも英語でも可能です。
+
 ### コード分析
 
 ```bash
 /nabledge-6 code-analysis
 ```
 
+現在のプロジェクトのコードをNablarchの観点から分析します。Actionクラス、ハンドラ構成、データベースアクセスパターンなどを評価し、改善提案を提供します。
+
 ## カバー範囲
 
 ### Nablarchバージョン

…/nabledge-6/plugin/marketplace-README.md .claude/marketplace/README.md.claude/skills/nabledge-6/plugin/marketplace-README.md renamed to .claude/marketplace/README.md .claude/skills/nabledge-6/plugin/marketplace-README.md renamed to .claude/marketplace/README.md

@@ -17,6 +17,11 @@ if [ ! -d "$SOURCE_DIR/.claude/skills/nabledge-6" ]; then
   exit 1
 fi
 
+if [ ! -d "$SOURCE_DIR/.claude/marketplace" ]; then
+  echo "Error: Source directory does not contain .claude/marketplace"
+  exit 1
+fi
+
 # Create marketplace directories
 echo "Creating marketplace directory structure..."
 mkdir -p "$DEST_DIR/.claude-plugin"
@@ -25,11 +30,11 @@ mkdir -p "$DEST_DIR/plugins/nabledge-6/skills/nabledge-6"
 
 # Copy marketplace.json to root
 echo "Copying marketplace.json..."
-cp "$SOURCE_DIR/.claude/skills/nabledge-6/plugin/marketplace.json" "$DEST_DIR/.claude-plugin/"
+cp "$SOURCE_DIR/.claude/marketplace/.claude-plugin/marketplace.json" "$DEST_DIR/.claude-plugin/"
 
 # Copy marketplace README and LICENSE to root
 echo "Copying marketplace README and LICENSE..."
-cp "$SOURCE_DIR/.claude/skills/nabledge-6/plugin/marketplace-README.md" "$DEST_DIR/README.md"
+cp "$SOURCE_DIR/.claude/marketplace/README.md" "$DEST_DIR/README.md"
 cp "$SOURCE_DIR/LICENSE" "$DEST_DIR/"
 
 # Copy nabledge-6 plugin files

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

@@ -24,7 +24,7 @@ jobs:
           INFRA_ONLY=true
           while IFS= read -r file; do
             if [[ ! "$file" =~ ^\.github/ ]] && \
-               [[ ! "$file" =~ plugin/marketplace ]] && \
+               [[ ! "$file" =~ \.claude/marketplace ]] && \
                [[ "$file" != *"transform-to-plugin.sh"* ]]; then
               INFRA_ONLY=false
               break
@@ -33,8 +33,8 @@ jobs:
 
           # If non-infrastructure files changed, require version update
           if [ "$INFRA_ONLY" = false ]; then
-            if ! echo "$CHANGED_FILES" | grep -q "plugin/plugin.json\|plugin/CHANGELOG.md"; then
-              echo "Error: plugin.json or CHANGELOG.md must be updated before sync"
+            if ! echo "$CHANGED_FILES" | grep -q "plugin/plugin.json\|plugin/CHANGELOG.md\|marketplace/.claude-plugin/marketplace.json"; then
+              echo "Error: plugin.json, CHANGELOG.md, or marketplace.json must be updated before sync"
               exit 1
             fi
           else