fix: restrict Bash tool access in create-marketplace command

Change unrestricted `Bash` to `Bash(mkdir:*)` following the
least-privilege security principle documented in the
command-development skill.

The command only needs mkdir for directory creation, so
unrestricted Bash access was unnecessary and inconsistent
with the sister command create-plugin.md.

Fixes #106

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

Author: sjnims

plugins/plugin-dev/commands/create-marketplace.md

@@ -1,7 +1,7 @@
 ---
 description: Create plugin marketplaces with guided workflow
 argument-hint: [marketplace-description]
-allowed-tools: Read, Write, Edit, Grep, Glob, Bash, TodoWrite, AskUserQuestion, Skill, Task
+allowed-tools: Read, Write, Edit, Grep, Glob, Bash(mkdir:*), TodoWrite, AskUserQuestion, Skill, Task
 ---
 
 # Marketplace Creation Workflow