Feature: Add 'clawatch update' command

[GalDayan]

Problem

Users need a simple way to update clawatch to the latest version without manually running npm/yarn commands.

Proposed Solution

Add a clawatch update command that:

• Checks for the latest version on npm
• Shows current vs. latest version
• Prompts to update if newer version available
• Handles the update process automatically

User Story

As a clawatch user, I want to run clawatch update so that I can easily keep my CLI up to date without leaving the tool.

Acceptance Criteria

• Command clawatch update exists
• Shows current installed version
• Fetches latest version from npm registry
• Displays comparison (current vs. latest)
• If up to date: shows "Already on latest version"
• If outdated: prompts user to update (Y/n)
• On Y: runs update command (npm/yarn global update)
• Shows success/failure message
• Works across npm, yarn, pnpm package managers

Edge Cases

• What if user doesn't have npm/yarn/pnpm? → Show error with install instructions
• What if registry is unreachable? → Graceful timeout + error message
• What if user installed via npx? → Show message that update isn't applicable
• Global vs. local install? → Detect install type, update accordingly

Open Questions

• Should it support clawatch update --check (check only, no prompt)?
• Should it auto-check on startup (like Homebrew)?
• Version pinning support?

Priority

P2 (nice to have, improves DX)

Requested by: Anas Dweik