Rename to liberty-global-gateway and add credential-free probe (2.0.0)

The /rest/v1 API is not specific to the Compal-built F3896LG: the firmware's
own web UI gates on five model IDs (CH7465LG, F3896LG, F3897LG, F5685LGB,
F5685LGE) across nine operator skins (Ziggo, UPC, Virgin Media, Unitymedia,
Sunrise, Yallo, Munro, Lumina, Grand Slam), and the F3896LG reports Sagemcom
rather than Compal. The old name named the wrong vendor and one model out of
five, so the package is now liberty-global-gateway.

- KNOWN_MODELS / KNOWN_SKINS / KNOWN_MANUFACTURERS from the firmware bundle.
- Localization model + probe(): unauthenticated identification of a gateway,
  yielding "Ziggo SmartWifi modem (F3896LG)". This is what makes
  zero-configuration discovery possible in the Home Assistant integration.
- Compal* exceptions and CompalClient stay as aliases; nothing breaks.
- Fixed stale docstrings still claiming the gateway has no logout endpoint.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

compalf3896lg 1.3.0 — writes + more reads

compalf3896lg 1.2.0 — WAN/provisioning + many read-only endpoints

compalf3896lg 1.1.0 — logout, hosts timeout, event log + registration

compalf3896lg 1.0.0 — published to PyPI