Linux installer assumes `brew`

[eharris128]

For reference, I am on Ubuntu 24.04

Not so much a breaking issue, more like, funky UX:

code-notify setup
🚀 Code-Notify Setup Wizard

ℹ️ Checking Claude Code installation...
✅ Claude Code found at: /home/evan/.claude

ℹ️ Checking notification system...
⚠️ terminal-notifier not found

For the best experience, install terminal-notifier:
  brew install terminal-notifier

Would you like to install it now? (y/n) y
ℹ️ Installing terminal-notifier...
/home/evan/.code-notify/lib/code-notify/commands/global.sh: line 402: brew: command not found
❌ Failed to install terminal-notifier
ℹ️ You can install it manually later