feat: add Samsung Air Monitor Plus support (#210)

New device family: a standalone, battery-powered air-quality sensor
puck (ASM-KR-TP1-22-* board) with no controllable-appliance state at
all -- no /power/*, only /energy/battery/vs/0. Routes via both /oic/d
('x.com.st.d.airqualitysensor', confirmed against the real dump) and
the 'ASM' modelNum board token as a fallback.

/sensors/vs/0 reuses air_purifier.AIR_QUALITY's existing {type, value}
items-list decode (common.sensor_item_value) for dust/fine_dust/
super_fine_dust/odor/clean_level, sharing those capabilities' catalog
entries, and adds a CO2 reading those families don't report. The
particulate sensors deliberately get no pm10/pm25/pm1 device_class:
the values read as physically consistent (coarser >= finer) but
Samsung's own two-tier dust naming doesn't confirm where this board's
three-tier split actually maps, and mislabeling a read-side unit is a
standing, not one-shot, kind of wrong -- exposed as plain named
sensors instead. Humidity, battery/charging, and the informational air
quality standard are otherwise straightforward field reads.

/dnd/vs/0 (do-not-disturb window) is a flagged educated guess: the
write contract mirrors the read side's own string/time-format shape
(the safest kind of guess) but has no idle-vs-active dump to confirm
it end-to-end, so it's called out as such in code and will need a
reporter to verify on real hardware. /keepnormalstate/vs/0 and
/sensordatasinks/vs/0 are genuinely opaque (single unexplained value,
no supported-values list) and are ignored rather than guessed at.

Locked in with a scrubbed fixture, golden, and capability tests.

tests/test_golden_regression.py

@@ -871,6 +871,27 @@ def test_registry_reproduces_golden_state_keys_for_air_dresser_tp1_21():
     )
 
 
+def test_registry_reproduces_golden_state_keys_for_air_monitor():
+    """Samsung Air Monitor Plus (ASM-KR-TP1-22-ACMB1M, issue #210) -- a
+    standalone battery-powered air-quality sensor puck, the first device
+    this integration has no controllable-appliance concept for at all (no
+    /power/*, only /energy/battery/vs/0). Routes via both /oic/d
+    ('x.com.st.d.airqualitysensor') and the 'ASM' modelNum board token.
+    Reuses air_purifier.AIR_QUALITY's /sensors/vs/0 decode
+    (common.sensor_item_value) for dust/fine_dust/super_fine_dust/odor/
+    clean_level, adding a CO2 reading those families don't report. Binds
+    cleanly with zero unbound hrefs."""
+    from tests.conftest import _load_device
+    resources = _load_device('air_monitor')
+    golden = json.loads((GOLDEN / 'air_monitor.json').read_text())
+    state_keys = _new_state_keys('air_monitor', resources)
+    assert set(state_keys) == set(golden['state_keys']), (
+        f"state_keys mismatch:\n"
+        f"  extra:   {sorted(set(state_keys) - set(golden['state_keys']))}\n"
+        f"  missing: {sorted(set(golden['state_keys']) - set(state_keys))}"
+    )
+
+
 def test_registry_reproduces_golden_state_keys_for_air_purifier_vtww():
     """A-VTWW-TP2-21-COMMON BESPOKE Cube Air (issue #151) -- reports no
     oneUiVersion; resolved via the '-VTWW-' modelNum token fallback into