[BUG] False update notification despite being on latest version (2.1.6)

Description

Claude Code is showing an "Update available! Run: brew upgrade claude-code" message even though the latest version is already installed.

Environment

• Current version: 2.1.6 (confirmed with claude --version)
• Homebrew latest version: 2.1.6 (confirmed with brew info claude-code)
• Platform: macOS
• OS Version: Darwin 25.2.0

Expected Behavior

No update notification should be shown when already on the latest version.

Actual Behavior

Update notification is displayed incorrectly:

Update available! Run: brew upgrade claude-code

Steps to Reproduce

1. Install Claude Code 2.1.6 via Homebrew
2. Verify current version with claude --version (shows 2.1.6)
3. Verify Homebrew has no newer version with brew info claude-code (shows 2.1.6 is latest)
4. Run Claude Code
5. Observe false update notification

Additional Context

The version check logic appears to be incorrectly triggering the update prompt.