refactor: move MCP tools to src/tools/ directory

[fahd04]

Summary

This PR extracts MCP tool implementations from src/index.ts into separate files in src/tools/ directory, addressing issue #52.

Changes

New directory structure:

src/tools/
├── index.ts                  # Re-exports all tools
├── types.ts                  # Shared types and interfaces
├── shell-start.ts
├── shell-send.ts
├── shell-read.ts
├── shell-screenshot.ts
├── shell-stop.ts
├── shell-record-start.ts
└── shell-record-stop.ts

Each tool file contains:

• Tool schema definition
• Tool implementation function
• Helper functions specific to that tool

Benefits

• ✅ Reduced src/index.ts from ~700 lines to 359 lines (almost 50% reduction)
• ✅ Better separation of concerns
• ✅ Easier to find and modify individual tools
• ✅ Simpler testing per tool
• ✅ Improved code maintainability

Testing

• ✅ All tests pass (npm test)
• ✅ Build succeeds (npm run build)
• ✅ Linting passes (npm run lint)
• ✅ No functional changes - purely refactoring

Checklist

• Follows conventional commit format
• All tools extracted to separate files
• Shared types moved to src/tools/types.ts
• All tests passing
• Linting passes
• Build succeeds

Closes #52