refactor: move MCP tools to src/tools/ directory

[dwmkerr]

Summary

Extract MCP tool implementations from src/index.ts into separate files in src/tools/.

Current State

All tools are defined inline in src/index.ts, making it large (~700 lines) and harder to maintain.

Proposed Structure

src/
├── index.ts           # Server setup, transport, tool registration
└── tools/
    ├── index.ts       # Re-exports all tools
    ├── shell-start.ts
    ├── shell-stop.ts
    ├── shell-send.ts
    ├── shell-read.ts
    ├── shell-screenshot.ts
    ├── shell-record-start.ts
    ├── shell-record-stop.ts
    ├── shell-attach.ts
    └── shell-detach.ts

Benefits

• Easier to find and modify individual tools
• Better separation of concerns
• Simpler testing per tool