[FEATURE] Better Monorepo Support

Environment

• Platform (select one):
• [x] Anthropic API
• [ ] AWS Bedrock
• [ ] Google Vertex AI
• [ ] Other: <!-- specify -->
• Claude CLI version: 1.0.29<!-- output of claude --version -->
• Operating System: Linux
• Terminal: Ghostty

Bug Description

I have a monorepository and I put a .mcp.json and some common commands in .claude/commands; but the way we work within the monorepo is from within service directories.

It would be nice if Claude would detect shared MCP and Commands within a Git root, by searching up.