Add occupancy binary_sensor for presence detectors (BWM)

[ernetas]

Summary

JUNG presence/motion detectors (Measurement "BWM" functions) report detection as a quantity datapoint with an empty unit and a 0/1 value (label Presence Detected). sensor.py only surfaces quantities that have a unit, so presence — the whole point of a motion sensor — was silently dropped. The diagnostics "unhandled types" check can't catch this because Measurement/quantity are both already-handled types; it was only visible in the raw WebSocket frames (spotted in a shared diagnostics dump).

Changes

• binary_sensor.py (new) — discovers any quantity datapoint whose label denotes presence and exposes it as BinarySensorDeviceClass.OCCUPANCY. on when the value is non-zero; None for a non-finite value (a bare NaN != 0 is misleadingly truthy, so it's guarded).
• const.py — is_presence_quantity() is the single split point (matches presence/occupancy/motion; deliberately not Present Illuminance).
• sensor.py — skips presence quantities so the two platforms never double-expose the same datapoint.
• __init__.py — registers Platform.BINARY_SENSOR.
• CLAUDE.md + tests updated; bump manifest to 1.2.2.

Device-class note: chose OCCUPANCY (label is "Presence Detected"; these hold state while occupied) over MOTION (instantaneous pulses).

Validation

• 142 tests pass (2 new for is_presence_quantity); ruff check/format clean; mypy clean.
• Simulated against the real diagnostics data: 3 new occupancy binary sensors discovered, the 3 illuminance sensors preserved, no overlap.

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