test(discovery): fixtures for the parsers, the bounded sweep and the surfaces

tests/test_installed_apps.py is new and is where the discovery claims are
pinned. NO REAL SHIELD WAS AVAILABLE, so the command output is fixture-based
in the documented Android shapes — `pm list packages` lines, the verbose
`resolve-activity` header followed by `package/activity`, and `pm dump`
carrying `application-label` — including a localized label (the default
locale wins), a label-less app (a definitive negative, and still a row) and
the launcher (a system app that must be present).

Covered: both parsers plus their tolerances (noise, duplicates, blank,
a bare `package/activity` line, the settings entry point that is not a
launcher), the user+launcher merge and its de-duplication, the icon
heuristic and that it is always a string, the sweep's commands, its
concurrency bound (peak <= APP_SWEEP_CONCURRENCY and > 1, so it is bounded
AND genuinely concurrent), cache reuse with zero shells, the TTL, shared
sweeps for concurrent callers, and every degradation path (no poller,
disconnected, mute transport — empty list, no loop, no raise). The sensor's
count/table/reason and the "a failed refresh is a no-op, not an exception"
behaviour are pinned too.

The config-flow side is in tests/test_config_flow_ux.py: the table lists
every discovered app, a discovered app the map never mentions is appended,
the user's name wins for the same package, an `mdi:` value never reaches the
icon column, rendering issues no shell, the Discover row runs one forced
sweep and returns to the menu, a failed sweep still renders, and the merged
table round-trips into the saved options.

Also: tests/test_config_flow_real_ha.py learns the new row, the standalone
stub accepts `description_placeholders` (which the apps form now passes),
and the state=6 wording in media_session.py/media_player.py is the t57
UNIT 0c reword.

tests/test_standalone_setup.py

@@ -149,12 +149,16 @@ def _install_stubs() -> None:
                 raise DiscoveryDedupAbortError("already_in_progress")
 
     class OptionsFlow:
-        def async_show_form(self, *, step_id, data_schema=None, errors=None):
+        def async_show_form(
+            self, *, step_id, data_schema=None, errors=None,
+            description_placeholders=None,
+        ):
             return {
                 "type": "form",
                 "step_id": step_id,
                 "errors": dict(errors or {}),
                 "data_schema": data_schema,
+                "description_placeholders": dict(description_placeholders or {}),
             }
 
         def async_show_menu(self, *, step_id, menu_options, sort=False,
@@ -1306,7 +1310,7 @@ class TestAppsMapOptionsEditor:
         assert result["type"] == "form"
         fields = getattr(result["data_schema"], "schema", result["data_schema"])
         suggested = fields.get("__suggested__", {})
-        assert suggested["app_name_map"] == "ar.tvplayer.tv=TiviMate"
+        assert suggested["app_name_map"] == "ar.tvplayer.tv=TiviMate"  # t57
         # the editor carried the existing map through the defaults path
         assert flow._options["app_name_map"] == {"ar.tvplayer.tv": "TiviMate"}