feat(adb_command): selectable target, strict resolution, and a real response (t14)

The user's live run could not select his Shield for
nvidia_shield.adb_command, so he ran his diagnostics through the deprecated
androidtv integration instead. Measured against the installed HA (2026.10.1),
the cause is a contract, not a bug in the handler:

* ServiceRegistry.async_register has NO target parameter, so a target cannot be
  declared at registration;
* the frontend renders the target picker from the service DESCRIPTION, which
  HA builds from services.yaml or from the runtime async_set_service_schema —
  and the runtime description WINS.

So async_setup now registers with supports_response=OPTIONAL and publishes
ADB_COMMAND_SERVICE_DESCRIPTION (target: {entity: [{domain: media_player}]},
fields, prose mirrored in strings.json/translations/en.json and pinned against
both by a test). No services.yaml is needed, and none is added.

The target resolution is strict, because the failure mode of guessing is a raw
shell command on the wrong device: exactly one PARTICIPANT, told apart as
no_target (nothing selected), unsupported_target (not a participant / option
off / another integration's entity) and ambiguous_target (two selected — sent
to neither). Accepts what HA actually sends: entity_id as text or as the LIST a
picked target produces, and device_id (an automation targeting the DEVICE),
expanded only through this integration's own registry entries and only to media
players. The output now comes back in the response under adb_response — the key
the user's captures read — while an unreachable Shield stays adb_unavailable,
an error rather than an empty response, and a call that does not ask for a
response is unchanged.

Evidence: 12 real-HA tests (new tests/test_adb_command_real_ha.py) drive the
real service registry, the real get_services websocket payload (the exact JSON
bytes the browser parses: target present, response optional, both fields) and
real async_call for every shape above. t14's CI gate globs tests/test_*real_ha.py
so a new real-HA file cannot skip silently; the skip/empty-collection guards stay
and were executed. The real-HA probe also caught async_entries_for_device being
a MODULE-LEVEL helper (not a registry method) that the stub had hidden, so the
drift gate's owner map now covers async_register, async_set_service_schema and
async_entries_for_device, with the call-argument floor raised 44 -> 52.

Verify: suites 681/4 and 682/3; real-HA 38 + the new file 12 (50 with the glob);
ruff clean; drift exit 0 (54 call arguments).

tests/test_adb_command_target.py

@@ -0,0 +1,121 @@
+"""t14: the adb_command ACTION is selectable — the contract HA reads.
+
+The user's report was that the Shield could not be selected for the
+``nvidia_shield.adb_command`` action, so he ran his diagnostics through the
+deprecated ``androidtv`` integration instead. The cause was measured against the
+installed Home Assistant (2026.10.1), not guessed:
+
+* ``ServiceRegistry.async_register`` takes no ``target`` — a target CANNOT be
+  declared at registration;
+* the frontend's target picker comes from the service DESCRIPTION, which HA builds
+  from ``services.yaml`` or from ``homeassistant.helpers.service.async_set_service_schema``,
+  and the runtime description WINS;
+* therefore THIS integration must publish a description carrying
+  ``target: {entity: [{domain: media_player}]}`` — that is the picker.
+
+This file pins the published contract itself, without any HA installed: the
+description, and the copy in BOTH translation files. The registration and the
+resolution are exercised in ``test_command_routing.py::TestAdbCommandService``
+(stubs) and in ``tests/test_adb_command_real_ha.py`` (real HA).
+"""
+
+from __future__ import annotations
+
+import json
+from pathlib import Path
+
+import pytest
+
+_ROOT = Path(__file__).resolve().parent.parent
+_SHIELD = _ROOT / "custom_components" / "nvidia_shield"
+
+
+@pytest.fixture(name="const")
+def const_fixture():
+    """The integration's const module, loaded by path like every other test."""
+    import sys
+
+    import conftest
+
+    if "nsh.const" not in sys.modules:
+        conftest._load_module("nsh.const", conftest._SHIELD_DIR / "const.py")
+    return sys.modules["nsh.const"]
+
+
+def _strings(name: str) -> dict:
+    return json.loads((_SHIELD / name).read_text(encoding="utf-8"))
+
+
+class TestThePublishedTarget:
+    """What HA is told the action accepts."""
+
+    def test_the_target_is_the_shields_media_player_entity(self, const):
+        assert const.ADB_COMMAND_SERVICE_TARGET == {
+            "entity": [{"domain": const.ADB_COMMAND_TARGET_DOMAIN}]
+        }
+        assert const.ADB_COMMAND_TARGET_DOMAIN == "media_player"
+
+    def test_the_description_carries_the_target_and_the_two_fields(self, const):
+        description = const.ADB_COMMAND_SERVICE_DESCRIPTION
+
+        # the picker: without this key the UI offers no Shield at all
+        assert description["target"] is const.ADB_COMMAND_SERVICE_TARGET
+        assert set(description["fields"]) == {"command", "entity_id"}
+        assert description["fields"]["command"]["required"] is True
+        # a plain (non-required) field: the TARGET is what selects the Shield, and
+        # an entity_id given anyway still has to point at a participant
+        assert "required" not in description["fields"]["entity_id"]
+
+    def test_the_response_key_is_the_one_the_old_integration_returned(self, const):
+        # the user's captures read `adb_response`; keeping the name means a template
+        # written against `androidtv.adb_command` keeps working
+        assert const.ADB_COMMAND_RESPONSE_KEY == "adb_response"
+
+
+class TestTheCopyMatchesBothTranslationFiles:
+    """The description's prose is duplicated in the translations — so it cannot drift.
+
+    ``strings.json``/``translations/en.json`` are where HA's translations live and
+    the description is what the frontend receives; the two copies must stay
+    identical, and every raised translation_key needs copy in BOTH files or the user
+    sees a bare key (t29's lesson, applied to t14's two new keys).
+    """
+
+    @pytest.mark.parametrize("name", ["strings.json", "translations/en.json"])
+    def test_the_service_copy_matches_the_description(self, const, name):
+        service = _strings(name)["services"]["adb_command"]
+        description = const.ADB_COMMAND_SERVICE_DESCRIPTION
+
+        assert service["name"] == description["name"]
+        assert service["description"] == description["description"]
+        for field, copy in description["fields"].items():
+            assert service["fields"][field]["name"] == copy["name"]
+            assert service["fields"][field]["description"] == copy["description"]
+
+    @pytest.mark.parametrize("name", ["strings.json", "translations/en.json"])
+    def test_the_new_exception_keys_have_copy(self, const, name):
+        exceptions = _strings(name)["exceptions"]
+
+        for key in ("no_target", "ambiguous_target", "unsupported_target"):
+            assert exceptions[key]["title"], (name, key)
+            assert exceptions[key]["message"], (name, key)
+
+        # the placeholders the handler fills in are the ones the copy names
+        assert "{entity_id}" in exceptions["ambiguous_target"]["message"]
+        assert "{entity_id}" in exceptions["unsupported_target"]["message"]
+        assert "{service}" in exceptions["no_target"]["message"]
+
+    def test_both_files_are_identical(self):
+        # they are two copies of the same English copy — a divergence would mean one
+        # of them is dead weight
+        assert (_SHIELD / "strings.json").read_text(
+            encoding="utf-8"
+        ) == (_SHIELD / "translations" / "en.json").read_text(encoding="utf-8")
+
+    def test_the_entity_field_copy_names_the_picker(self):
+        # the field the YAML caller passes has to say what to pass, now that the
+        # picker is the primary way in
+        for name in ("strings.json", "translations/en.json"):
+            copy = _strings(name)["services"]["adb_command"]["fields"]["entity_id"]
+            assert "media_player" in copy["description"]
+            assert "device_id" in copy["description"]