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_batch.py

@@ -8,49 +8,50 @@ empty" apart from "haven't polled it yet" and created phantom always-
 "unknown" entities either way. is_stub_rep/parse_device0_batch now keep the
 two shapes distinct.
 """
+
 from custom_components.localthings.registry.batch import is_stub_rep, parse_device0_batch
 
 
 class TestIsStubRep:
     def test_true_for_bare_href_marker(self):
-        assert is_stub_rep({'href': '/energy/consumption/vs/0'}) is True
+        assert is_stub_rep({"href": "/energy/consumption/vs/0"}) is True
 
     def test_false_for_genuinely_empty_rep(self):
         assert is_stub_rep({}) is False
 
     def test_false_for_populated_rep(self):
-        assert is_stub_rep({'x.com.samsung.da.cumulativePower': '58900'}) is False
+        assert is_stub_rep({"x.com.samsung.da.cumulativePower": "58900"}) is False
 
     def test_false_for_href_plus_data(self):
         """A real, populated rep may legitimately echo 'href' alongside
         actual fields -- only a rep with *no other keys* is the stub."""
-        assert is_stub_rep({'href': '/x/0', 'value': True}) is False
+        assert is_stub_rep({"href": "/x/0", "value": True}) is False
 
 
 class TestParseDevice0Batch:
     def test_stub_rep_kept_distinct_from_genuine_empty(self):
         device0 = [
             {},
-            {'href': '/energy/consumption/vs/0', 'rep': {'href': '/energy/consumption/vs/0'}},
-            {'href': '/sabbath/vs/0', 'rep': {}},
+            {"href": "/energy/consumption/vs/0", "rep": {"href": "/energy/consumption/vs/0"}},
+            {"href": "/sabbath/vs/0", "rep": {}},
         ]
         resources = parse_device0_batch(device0)
-        assert is_stub_rep(resources['/energy/consumption/vs/0']) is True
-        assert is_stub_rep(resources['/sabbath/vs/0']) is False
-        assert resources['/sabbath/vs/0'] == {}
+        assert is_stub_rep(resources["/energy/consumption/vs/0"]) is True
+        assert is_stub_rep(resources["/sabbath/vs/0"]) is False
+        assert resources["/sabbath/vs/0"] == {}
 
     def test_populated_rep_passes_through_unchanged(self):
         device0 = [
             {},
-            {'href': '/door/cooler/0', 'rep': {'openState': 'Close'}},
+            {"href": "/door/cooler/0", "rep": {"openState": "Close"}},
         ]
         resources = parse_device0_batch(device0)
-        assert resources['/door/cooler/0'] == {'openState': 'Close'}
+        assert resources["/door/cooler/0"] == {"openState": "Close"}
 
     def test_skips_entries_without_href(self):
-        device0 = [{}, {'rep': {'a': 1}}]
+        device0 = [{}, {"rep": {"a": 1}}]
         assert parse_device0_batch(device0) == {}
 
     def test_skips_non_dict_rep(self):
-        device0 = [{}, {'href': '/x/0', 'rep': 'not-a-dict'}]
+        device0 = [{}, {"href": "/x/0", "rep": "not-a-dict"}]
         assert parse_device0_batch(device0) == {}