Fix expired qBittorrent sessions without a ROMarr restart

[BlizzHacker]

Summary

• refresh expired qBittorrent WebUI sessions after a 401/403
• retry both reads and writes exactly once after a successful re-login
• keep a rejected refresh unhealthy and avoid retry loops

Why

ROMarr keeps its qBittorrent client for the lifetime of the process, but qBittorrent sessions expire. Once that happened, health checks, completed-download polling, and new grabs stayed broken until ROMarr was restarted even though the stored credentials were valid.

This was reproduced against the live qBittorrent 5.x instance: a ROMarr restart restored the connection immediately. The deployed patch now keeps the session self-healing.

Verification

• python -m pytest tests/test_qbittorrent_login.py tests/test_qbittorrent_excluded_files.py -q — 22 passed
• full suite — 1,975 passed, 2 skipped, 1 deselected; the only two failures are the Windows App Execution Alias for bash.exe, not Python/application failures
• live ROMarr 0.8.0 after deployment: qBittorrent configured=true, ok=true; RomM ok=true, readable=true; GG Requestz ok=true