Add Wi‑Fi signal strength support for NEO

[realholgi]

Summary

• Add Wi‑Fi signal-strength support for NEO via configuration register 76.
• Parse config-read response values using the declared value length, preventing trailing protocol data from becoming
  part of the state.
• Route config-read state updates through the Home Assistant MQTT client and retain them on the target broker.

Tests

• Add coverage for NEO Wi‑Fi RSSI parsing with trailing protocol data.
• Verify NEO Wi‑Fi discovery metadata and retained config-state publishing.
• pytest: 360 passed, 1 skipped.