Update notification shows when already on latest Homebrew version

Description

Claude Code displays "Update available! Run: brew upgrade claude-code" even when the latest version is already installed via Homebrew.

Steps to Reproduce

1. Install Claude Code via Homebrew
2. Run brew update && brew upgrade claude-code
3. Homebrew confirms you're on the latest version
4. Launch claude - still shows "Update available" notification

Environment

• Claude Code version: 2.1.14
• Installation method: Homebrew cask
• Platform: macOS (Darwin 25.2.0)
• Homebrew info: Shows 2.1.14 as both installed and latest available

Expected Behavior

No update notification should appear when the installed version matches the latest available Homebrew version.

Actual Behavior

"Update available! Run: brew upgrade claude-code" message appears despite being on the latest version.