fix: Windows-compatible connect tests (path prefix + file permissions)

TestConfigPath_AllClients: use TempDir and check IsAbs instead of Unix
path prefix (APPDATA-based paths don't start with homeDir on Windows).
TestConnect_FilePermissionsPreserved: skip on Windows where Unix
permissions are not supported.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>