Fixes stack overflow and database initialization failures when running bd on WSL2 with Docker Desktop bind mounts.
## Problem
The bd CLI crashed with stack overflow when running on WSL2 with repositories on Docker Desktop bind mounts (/mnt/wsl/docker-desktop-bind-mounts/...). SQLite WAL mode fails with 'locking protocol' error on these network filesystems.
## Solution
- Expand WAL mode detection to identify Docker bind mounts at /mnt/wsl/* (in addition to Windows paths at /mnt/[a-zA-Z]/)
- Fall back to DELETE journal mode on these problematic paths
- Add comprehensive unit tests for path detection
Fixes GH #1224, relates to GH #920
Co-authored-by: maphew <matt.wilkie@gmail.com>