Add dehumidifier display switch and watertank lighting (issues #271, #231)

The TP1X_DA_AC_DHM_01001_0000 revision (model AY70H18100GTD) additionally
reports /display/vs/0 (same shape as air_purifier's screen toggle, reused
directly) and /watertank/lighting/vs/0 (on/off, color, and brightness for
the tank's ambient light, plus a diagnostic alarm-status flag). Both issues
submitted the identical dump, so one fix covers both reports.

Also adds x.com.st.d.dehumidifier to the /oic/d device-type routing table
now that a dump confirms it.

tests/test_golden_regression.py

@@ -1226,6 +1226,23 @@ def test_registry_reproduces_golden_state_keys_for_range_ne6516a():
     )
 
 
+def test_registry_reproduces_golden_state_keys_for_dehumidifier_tp1x_dhm01001():
+    """TP1X_DA_AC_DHM_01001_0000 revision (issues #271/#231) additionally
+    reports /display/vs/0 (air_purifier.DISPLAY's exact shape, reused as-is)
+    and /watertank/lighting/vs/0 (new WATERTANK_LIGHTING capability), both
+    unbound on the original issue #88 dump."""
+    from tests.conftest import _load_device
+
+    resources = _load_device("dehumidifier_tp1x_dhm01001")
+    golden = json.loads((GOLDEN / "dehumidifier_tp1x_dhm01001.json").read_text())
+    state_keys = _new_state_keys("dehumidifier_tp1x_dhm01001", 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_resources_from_batch_preferred_over_flat():
     from tests.conftest import _resources_from_dump