* refactor: split agent config and auth services
* chore: repoint wsl and global-fetch guards at split module paths
* fix: restore merge-base Claude CLI error propagation
Drop the secret-redaction rewriting added to Claude CLI error paths in the
refactor: spawn errors again reject with the original Error (preserving
.code/.errno/.syscall/.stack) and command output/auth-status logs are no
longer rewritten.
