Add ruff (lint + format) and ty (type checking) to the project

Adds [tool.ruff] and [tool.ty] config to pyproject.toml with a curated
ruff rule set (E, F, W, I, UP, B, C4, SIM, RUF, ASYNC, LOG, G, PIE, RET,
PERF, N), pins ruff/ty in requirements-dev.txt, reformats the whole tree
with `ruff format`, and fixes the pre-existing lint and type-check debt
those tools surfaced so both run clean.

Production-code type fixes include: HA's ConfigFlowResult vs. the
generic FlowResult in config_flow.py, narrowing BoundEntity.desc to its
platform-specific subclass (SelectDesc/NumberDesc/SensorDesc/etc.) via
cast() instead of an unchecked annotation, converting HA device_class
strings to their proper enum types, a resolve_registry callback typed
as `object` instead of `DeviceRegistry | None`, and a couple of other
narrow correctness fixes (CA key type validation, an index-out-of-bounds
false positive from an empty-tuple fallback, a bool/dict argument swap).

Test-file fixes are mechanical: narrowing SamsungEntityDescription to
the correct subclass via isinstance()/cast() before accessing
subclass-only fields, and asserting Optional write_fn/unit_fn fields
are set before calling them.

tests/test_ehs_capabilities.py

@@ -4,19 +4,20 @@
 HA-free like the rest of the suite: exercises the registry, discovery/
 flatten, and the zone/dhw mode and temperature write contracts.
 """
+
 from custom_components.localthings.registry.adapter import flatten
 from custom_components.localthings.registry.by_type import for_device_by_model
 from custom_components.localthings.registry.discovery import discover
 from custom_components.localthings.registry.entities import NumberDesc, SelectDesc, WaterHeaterDesc
-
 from tests.conftest import _load_device
 
 
 def _ehs():
-    resources = _load_device('ehs')
-    info = resources['/information/vs/0']
+    resources = _load_device("ehs")
+    info = resources["/information/vs/0"]
     reg = for_device_by_model(
-        info['x.com.samsung.da.modelNum'], info['x.com.samsung.da.description'],
+        info["x.com.samsung.da.modelNum"],
+        info["x.com.samsung.da.description"],
     )
     return reg, resources
 
@@ -38,7 +39,7 @@ def _desc(key):
 
 def test_model_resolves_to_ehs_registry():
     reg, _ = _ehs()
-    assert reg is not None and reg.name == 'ehs'
+    assert reg is not None and reg.name == "ehs"
 
 
 def test_no_unbound_hrefs():
@@ -53,72 +54,81 @@ def test_no_unbound_hrefs():
 
 def test_expected_state_keys_present():
     state = _state()
-    for key in ('zone_power', 'zone_mode', 'zone_temperature', 'zone_target_temperature',
-                'water_heater', 'away_mode', 'mute_once', 'alarm_code', 'energy_kwh'):
+    for key in (
+        "zone_power",
+        "zone_mode",
+        "zone_temperature",
+        "zone_target_temperature",
+        "water_heater",
+        "away_mode",
+        "mute_once",
+        "alarm_code",
+        "energy_kwh",
+    ):
         assert key in state, key
 
 
 def test_zone_temperature_reads_current_value():
     state = _state()
-    assert state['zone_temperature'] == 30.0
+    assert state["zone_temperature"] == 30.0
 
 
 def test_zone_target_temperature_reads_desired_value():
     state = _state()
-    assert state['zone_target_temperature'] == 5.0
+    assert state["zone_target_temperature"] == 5.0
 
 
 def test_zone_mode_reads_first_mode():
     state = _state()
-    assert state['zone_mode'] == 'Cool'
+    assert state["zone_mode"] == "Cool"
 
 
 def test_zone_mode_select_options_come_from_live_supported_modes():
     """Options are read live from x.com.samsung.da.supportedModes, not a
     hardcoded tuple -- so a future firmware with a different mode set is
     handled automatically."""
-    desc = _desc('zone_mode')
+    desc = _desc("zone_mode")
     assert isinstance(desc, SelectDesc)
-    assert desc.options_field == 'x.com.samsung.da.supportedModes'
+    assert desc.options_field == "x.com.samsung.da.supportedModes"
     assert desc.options == ()
 
 
 def test_zone_mode_write_contract():
-    desc = _desc('zone_mode')
-    path, body = desc.write_fn('Heat', {})
-    assert path == ['mode', 'vs', '0']
-    assert body == {'x.com.samsung.da.modes': ['Heat']}
+    desc = _desc("zone_mode")
+    path, body = desc.write_fn("Heat", {})
+    assert path == ["mode", "vs", "0"]
+    assert body == {"x.com.samsung.da.modes": ["Heat"]}
 
 
 def test_zone_power_reads_off():
     state = _state()
-    assert state['zone_power'] is False
+    assert state["zone_power"] is False
 
 
 def test_zone_power_write_contract():
-    desc = _desc('zone_power')
-    path, body = desc.write_fn('On', {})
-    assert path == ['power', 'vs', '0']
-    assert body == {'x.com.samsung.da.power': 'On'}
+    desc = _desc("zone_power")
+    path, body = desc.write_fn("On", {})
+    assert path == ["power", "vs", "0"]
+    assert body == {"x.com.samsung.da.power": "On"}
 
 
 def test_zone_target_temperature_write_contract():
-    desc = _desc('zone_target_temperature')
+    desc = _desc("zone_target_temperature")
     assert isinstance(desc, NumberDesc)
-    path, body = desc.write_fn('21.5', {})
-    assert path == ['temperatures', 'indoor', 'vs', '0']
-    assert body == {'x.com.samsung.da.desired': '21.5'}
+    path, body = desc.write_fn("21.5", {})
+    assert path == ["temperatures", "indoor", "vs", "0"]
+    assert body == {"x.com.samsung.da.desired": "21.5"}
 
 
 def test_zone_target_temperature_bounds_read_live():
     """min/max/step come from the device's own resource fields rather than
     a hardcoded constant -- see the adding-device-support skill's 'never
     hard-code the one dump's values' section."""
-    desc = _desc('zone_target_temperature')
-    rep = {'x.com.samsung.da.minimum': '5.0', 'x.com.samsung.da.maximum': '25.0'}
+    desc = _desc("zone_target_temperature")
+    rep = {"x.com.samsung.da.minimum": "5.0", "x.com.samsung.da.maximum": "25.0"}
     assert desc.native_min_fn(rep) == 5.0
     assert desc.native_max_fn(rep) == 25.0
-    assert desc.step_fn({'x.com.samsung.da.increment': '0.5'}) == 0.5
+    assert desc.step_fn({"x.com.samsung.da.increment": "0.5"}) == 0.5
     # No live field: falls back to a sane default rather than raising.
     assert desc.native_min_fn({}) == 5.0
     assert desc.native_max_fn({}) == 30.0
@@ -129,16 +139,16 @@ def test_zone_target_temperature_bounds_fall_back_together():
     """One end without the other is not a usable range: pairing a real
     device minimum with an invented default maximum looks plausible and is
     silently wrong, so a half-reported range falls back whole."""
-    desc = _desc('zone_target_temperature')
-    half = {'x.com.samsung.da.minimum': '10.0'}
+    desc = _desc("zone_target_temperature")
+    half = {"x.com.samsung.da.minimum": "10.0"}
     assert desc.native_min_fn(half) == 5.0
     assert desc.native_max_fn(half) == 30.0
 
 
 def test_zone_target_temperature_zero_increment_is_not_collapsed():
     """`or` would turn a genuine 0 into the 0.5 default (issue #160)."""
-    desc = _desc('zone_target_temperature')
-    assert desc.step_fn({'x.com.samsung.da.increment': '0'}) == 0.0
+    desc = _desc("zone_target_temperature")
+    assert desc.step_fn({"x.com.samsung.da.increment": "0"}) == 0.0
 
 
 def test_water_heater_entity_is_bound():
@@ -148,7 +158,7 @@ def test_water_heater_entity_is_bound():
     bound, _ = _bound()
     water_heaters = [b for b in bound if isinstance(b.desc, WaterHeaterDesc)]
     assert len(water_heaters) == 1
-    assert water_heaters[0].href == '/mode/dhw/vs/0'
+    assert water_heaters[0].href == "/mode/dhw/vs/0"
 
 
 def test_water_heater_reads_first_mode():
@@ -156,23 +166,31 @@ def test_water_heater_reads_first_mode():
     the entity's current_operation is derived from -- see climate.py's
     _first_mode for the identical pattern on the AC side."""
     state = _state()
-    assert state['water_heater'] == 'Eco'
+    assert state["water_heater"] == "Eco"
 
 
 def test_water_heater_write_targets():
     """DHW.entities[0].write_fn maps each (kind, value) command to the right
     vendor POST target and body -- power, mode and temperature only, no fan/
     swing/preset (the AC's climate.py has those; the DHW loop doesn't)."""
-    write = _desc('water_heater').write_fn
-    assert write(('power', True), {}) == (
-        ['power', 'dhw', 'vs', '0'], {'x.com.samsung.da.power': 'On'})
-    assert write(('power', False), {}) == (
-        ['power', 'dhw', 'vs', '0'], {'x.com.samsung.da.power': 'Off'})
-    assert write(('mode', 'Force'), {}) == (
-        ['mode', 'dhw', 'vs', '0'], {'x.com.samsung.da.modes': ['Force']})
-    assert write(('temperature', 45.0), {}) == (
-        ['temperatures', 'dhw', 'vs', '0'], {'x.com.samsung.da.desired': '45.0'})
-    assert write(('bogus', 1), {}) is None
+    write = _desc("water_heater").write_fn
+    assert write(("power", True), {}) == (
+        ["power", "dhw", "vs", "0"],
+        {"x.com.samsung.da.power": "On"},
+    )
+    assert write(("power", False), {}) == (
+        ["power", "dhw", "vs", "0"],
+        {"x.com.samsung.da.power": "Off"},
+    )
+    assert write(("mode", "Force"), {}) == (
+        ["mode", "dhw", "vs", "0"],
+        {"x.com.samsung.da.modes": ["Force"]},
+    )
+    assert write(("temperature", 45.0), {}) == (
+        ["temperatures", "dhw", "vs", "0"],
+        {"x.com.samsung.da.desired": "45.0"},
+    )
+    assert write(("bogus", 1), {}) is None
 
 
 def test_dhw_power_and_temperature_declared_as_coverage():
@@ -181,7 +199,7 @@ def test_dhw_power_and_temperature_declared_as_coverage():
     their own entities -- declared as no-entity coverage caps so discover()
     reports no gap, same pattern as the AC's CLIMATE_CONSUMED_HREFS."""
     reg, _ = _ehs()
-    for href in ('/power/dhw/vs/0', '/temperatures/dhw/vs/0'):
+    for href in ("/power/dhw/vs/0", "/temperatures/dhw/vs/0"):
         caps = reg.capabilities.get(href)
         assert caps, href
         assert all(c.entities == () for c in caps), href
@@ -189,11 +207,11 @@ def test_dhw_power_and_temperature_declared_as_coverage():
 
 def test_away_mode_reads_off():
     state = _state()
-    assert state['away_mode'] is False
+    assert state["away_mode"] is False
 
 
 def test_away_mode_write_contract():
-    desc = _desc('away_mode')
-    path, body = desc.write_fn('On', {})
-    assert path == ['option', 'outgoing', 'vs', '0']
-    assert body == {'x.com.samsung.da.away': 'On'}
+    desc = _desc("away_mode")
+    path, body = desc.write_fn("On", {})
+    assert path == ["option", "outgoing", "vs", "0"]
+    assert body == {"x.com.samsung.da.away": "On"}