Used compact hashed isolation directory segments and the short m mount dir so long task ids are not copied into subagent working paths. Kept worktree cleanup compatible with legacy merged task-isolation directories. Fixes #3756
- Added the new `omp worktree` (`wt`) command with `list|clear`, `all/dry-run/json` options, and CLI registration. - Added `listWorktrees`/`clearWorktrees` flows that scan worktrees, classify orphaned entries, emit JSON, and call `worktree.prune`. - Replaced legacy path encoding with `hashPath` via `getWorktreeDir`, updating task isolation, storage keys, and PR checkout paths. - Added bounded PR worktree path retries before `git worktree add` and updated checkout-path tests for hashed names.