AC: quantize subdevice temperature writes against their own step (Opus review)

async_send_command handed write_fn/validate_fn the raw cache snapshot
(real, on-the-wire hrefs), not a subdevice-scoped view. Every other
consumer of a full resources dict (exists_fn, rep_fn, is_legacy_board,
...) reads through coordinator.canonical_resources() specifically to
avoid this; write_fn/validate_fn didn't, so on a composite AC (issue
#177) _temperature_step's resources.get(HREF_TEMP_CONTROL) saw the
master's /temperature/control/vs/0 instead of the subdevice's own
/temperature/control/vs/1, silently rounding a subdevice's 0.5-degree
write to a whole degree. The remote-control gate stays on the raw
snapshot -- /remotectrl/* is a shared, MAIN-only resource a
subdevice's owned-hrefs-only canonical view would drop entirely.

climate.py's target_temperature_step duplicated this same
read-in-order logic; pointed it at airconditioner._temperature_step
so the read and write paths can't drift again.

Also, from the same review:
- _quantize_temperature rejects non-finite floats (nan/inf survive
  float() but raise out of round()/division, escaping write_fn's
  documented None-on-bad-payload contract).
- Deduplicated the quantize-and-check block shared by the
  temperature_ocf/temperature branches of _climate_write.
- Added the /temperatures/vs/0 items[]-fallback test that was
  previously unreachable (every increment-carrying fixture also has
  /temperature/control/vs/0, which _temperature_step checks first).
- Added a coordinator-level test seeding an indexed subdevice with its
  own step, distinct from the master's, covering the fix above.
- The Towels/Bedding regression test now checks all 7 locale catalogs,
  not just English -- the bug is a code-mapping error, and
  test_every_language_mirrors_the_english_catalog only checks key
  topology, not values.

tests/test_coordinator_send_command.py

@@ -201,3 +201,33 @@ async def test_main_climate_write_unaffected_by_subdevice_translation(coordinato
 
     posted_path, _ = coordinator._session.post_calls[0]
     assert posted_path == ["power", "vs", "0"]
+
+
+async def test_indexed_subdevice_climate_write_quantizes_with_its_own_temperature_step(
+    coordinator,
+) -> None:
+    """A composite AC's write_fn (airconditioner._climate_write) reads the
+    temperature step off write_fn's own `resources` argument -- if
+    async_send_command handed it the raw cache snapshot (real, on-the-wire
+    hrefs) instead of this subdevice's canonical_resources() view, the
+    subdevice's own /temperature/control/vs/1 would be invisible under the
+    canonical HREF_TEMP_CONTROL key, and the write would quantize against
+    the master's step (or none at all) instead of its own."""
+    sub1 = Subdevice(kind="indexed", key="1", seed_path=("device", "1"))
+    coordinator._observe.apply(
+        "/temperature/control/vs/0",
+        {"x.com.samsung.da.increment": "1"},
+        source="poll",
+    )
+    coordinator._observe.apply(
+        "/temperature/control/vs/1",
+        {"x.com.samsung.da.increment": "0.5"},
+        source="poll",
+    )
+    bound = _climate_bound("/mode/vs/1", sub1)
+
+    await coordinator.async_send_command(bound, ("temperature_ocf", 24.5))
+
+    posted_path, posted_bytes = coordinator._session.post_calls[0]
+    assert posted_path == ["temperature", "desired", "1"]
+    assert cbor2.loads(posted_bytes) == {"temperature": 24.5}