Installer does not update launcher symlink when upgrading versions

Description

When upgrading Claude Code via the install script, the new binary is downloaded and placed in ~/.local/share/claude/versions/<version>, but the launcher symlink at ~/.local/bin/claude is not updated to point to the new version.

Steps to reproduce

# Starting from 2.1.97, install 2.1.112
curl -fsSL https://claude.ai/install.sh | bash -s -- 2.1.112

Installer output says success:

Setting up Claude Code...
✔ Claude Code successfully installed!
  Version: 2.1.112
  Location: ~/.local/bin/claude

But:

$ claude --version
2.1.97 (Claude Code)

$ ls -l ~/.local/bin/claude
lrwxr-xr-x  lance  staff  ~/.local/bin/claude -> ~/.local/share/claude/versions/2.1.97

$ ls ~/.local/share/claude/versions/
2.1.92   2.1.97   2.1.112

The new binary exists on disk but the symlink still points to the old version.

Expected behavior

After a successful install, ~/.local/bin/claude should be a symlink to the newly installed version (~/.local/share/claude/versions/2.1.112).

Workaround

ln -sfn ~/.local/share/claude/versions/2.1.112 ~/.local/bin/claude

Environment

• macOS (Darwin arm64)
• Shell: zsh
• Claude Code 2.1.97 -> 2.1.112 upgrade

# Fix the symlink to the latest version
ln -sfn "$(ls ~/.local/share/claude/versions/* | sort -V | tail -1)" ~/.local/bin/claude

# Remove old versions to prevent the buggy installer from reverting
ls ~/.local/share/claude/versions/* | sort -V | head -n -1 | xargs rm -f