Add Reticulum/LXMF integration for Home Assistant

Custom integration connecting Home Assistant to a Reticulum network over a
TCPClientInterface and exchanging LXMF messages, with an Assist conversation
bridge, notify entity, sensors (incl. interface telemetry), buttons, services,
bus events and device triggers.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

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+.claude/
+__pycache__/
+*.py[cod]
+.venv/
+venv/
+.env
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+*.egg-info/
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