/clear resets working directory, losing worktree context

Problem

When working inside a git worktree (or any directory navigated to during a session), running /clear resets the working directory back to the original launch directory instead of preserving the current working directory.

This is particularly dangerous with git worktrees because:

• You think you're still in the worktree on a feature branch
• You're actually back in the main project directory on main
• Any file edits or git operations now affect main instead of the worktree branch

Steps to Reproduce

1. Launch claude from a project root (e.g., ~/dev/my-project/)
2. Create or enter a worktree: cd .claude/worktrees/my-feature/
3. Do some work on the worktree branch
4. Run /clear to free up context
5. Check pwd and git branch — you're back in the original project root on main

Expected Behavior

/clear should preserve the current working directory so that:

• pwd remains the same after clear
• Git branch context is maintained
• File operations continue targeting the correct directory

Actual Behavior

/clear resets the session to the directory where claude was originally invoked, silently changing the git branch and file context.

Impact

• Silent data hazard: edits and commits land on main instead of the feature branch
• Worktree workflow broken: worktrees are designed for isolated work, but /clear breaks that isolation
• Forces users to either avoid /clear entirely or remember to cd back every time