Installation lock bug: --force flag doesn't work when Claude is running

Bug Description

claude install latest --force fails with a lock error even when using the --force flag, if Claude Code is currently running.

Steps to Reproduce

1. Start a Claude Code session
2. Run claude install latest --force from within Claude or another terminal
3. Observe the error:

✘ Installation failed

Could not install - another process is currently installing Claude. Please try
again in a moment.

Try running with --force to override checks

Root Cause

The installation process acquires a lock on the running binary (~/.local/share/claude/versions/X.X.XX). When Claude is running, the binary is locked by the OS, preventing updates.

Debug logs show:

2025-11-18T18:17:01.214Z [ERROR] Lock acquisition failed for /home/kuro/.local/share/claude/versions/2.0.45

The --force flag doesn't bypass this OS-level lock.

##Expected Behavior

The --force flag should allow installation while Claude is running, either by:

1. Installing to a new version path and updating the symlink (allowing next restart to use the new version)
2. Properly documenting that users must exit all Claude sessions before upgrading
3. Providing a clear error message explaining the actual issue

Current Behavior

The error message says "Try running with --force to override checks" but --force doesn't actually work.

Workaround

Exit all Claude Code sessions, then run the installation from a regular terminal:

claude install latest

Environment

• Claude Code version: 2.0.45
• Platform: Linux (Ubuntu)
• Installation method: Native build

Impact

Users cannot update Claude Code while using it, and the --force flag provides false hope that there's a solution.