feat: add Glob tool to agent-creator for detecting existing agents

Add Glob to the tools list enabling the agent to proactively scan for
existing agent files and detect naming conflicts before writing. This
aligns with the edge case documentation that mentions conflict handling.

Fixes #128

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

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

Author: sjnims

plugins/plugin-dev/agents/agent-creator.md

@@ -41,7 +41,7 @@ User describes agent-like functionality need without explicitly requesting agent
 # Explicit sonnet for complex agent generation reasoning
 model: sonnet
 color: magenta
-tools: Write, Read
+tools: Write, Read, Glob
 skills: agent-development
 ---