feat(discovery): enumerate the apps installed on the Shield (t57)

The live complaint ("it doesn't find all the apps") came from the curated
list: only four packages were ever offered, so anything the user had
installed elsewhere was invisible. The device knows its own apps.

ha_adb_common/installed_apps.py parses the two queries the sweep makes:

* `pm list packages -3` — every third-party (user-installed) package;
* `cmd package resolve-activity --brief -c android.intent.category.HOME`
  — the ACTIVE launcher, a system app that is nonetheless what the user
  opens, so it is appended rather than filtered away.

System apps are otherwise not enumerated (a Shield ships a few hundred and
they are not launchable apps); the parsers are tolerant of the noise a real
adb shell can prepend and of duplicate lines.

ShieldConnectionManager gains the sweep:
`async_refresh_installed_apps(force=False)` returns a cached
`[{package, name, icon}]` table, and `installed_apps()` is a pure read that
never issues a shell — so a state poll costs nothing.

Naming stays on the one path: the sweep calls `_dump_label`, the same
`pm dump` + parse + 24 h cache the entity path uses, now extracted so the
two cannot drift, including the t57 UNIT 0 rule that a fetch that returned
nothing is NOT cached. Labels are fetched APP_SWEEP_CONCURRENCY (4) at a
time with APP_SWEEP_SPACING (50 ms), so a typical Shield finishes in
seconds rather than the minutes a one-per-watchdog-cycle drain would take
while the socket still sees a trickle.

Failure is a normal outcome: no poller, a disconnected transport or a mute
shell stores an EMPTY table with a stamp and returns [], so nothing retries
in a loop and every surface degrades to "no discovered apps".

Icons: `pm dump` does NOT expose an app's icon resource — an extracted
APK's icon is a bitmap only its own code resolves — so this is honestly a
heuristic: APP_ICON_FALLBACKS (a curated package -> mdi: map) with
APP_ICON_GENERIC (mdi:television) for anything unknown, and always a string.

custom_components/nvidia_shield/ha_adb_common/installed_apps.py

@@ -0,0 +1,125 @@
+"""Discover the apps actually installed on the Shield (t57).
+
+The live complaint ("it doesn't find all the apps") came from the curated
+fallback list: only four packages were ever offered, so a user with Wholphin,
+SmartTube, Kodi, Plex or anything else saw nothing. The device knows its own
+apps, so this module asks it.
+
+The commands (both plain `pm`, available on Shield Experience 9 / Android 11
+with no extra permission beyond the ADB pairing this integration already has):
+
+* ``pm list packages -3``      — third-party (user-installed) packages, one
+  ``package:<id>`` line each. This is what the live complaint is about: an app
+  the user installed is a ``-3`` package.
+* ``cmd package resolve-activity --brief -c android.intent.category.HOME``
+  — the ACTIVE launcher (``com.google.android.tvlauncher/....MainActivity``).
+  A launcher is a system app, so it is not in ``-3``, yet it is exactly the app
+  a user sees and may want to name or launch — so it is added explicitly.
+
+System apps are otherwise NOT enumerated: the Shield ships a few hundred of
+them and they are not launchable apps a media-player source list wants. The
+one system app that matters (the launcher) is resolved, not filtered.
+
+Labels come from the existing ``pm dump`` + ``parse_application_label`` path and
+its 24 h cache (``ShieldConnectionManager.app_label``), so discovery adds no
+second naming mechanism.
+
+Icons are best effort and explicitly heuristic — see ``icon_for_package``.
+"""
+
+from __future__ import annotations
+
+import re
+
+#: One `pm list packages` line: ``package:com.example.app``.
+_PACKAGE_LINE_RE = re.compile(r"^package:(?P<package>[\w.]+)\s*$", re.MULTILINE)
+
+#: `resolve-activity --brief` prints ``package/activity`` on the last line,
+#: possibly preceded by the (verbose) intent header.
+_COMPONENT_RE = re.compile(r"^(?P<package>[\w.]+)/[\w.$]+$", re.MULTILINE)
+
+#: Activity components that belong to a launcher but are not what the user
+#: opens: settings/hidden entry points a HOME resolution can land on.
+_LAUNCHER_NOISE = ("com.android.tv.settings",)
+
+
+def parse_package_list(output: str | None) -> list[str]:
+    """The package ids in a ``pm list packages`` dump, in device order.
+
+    Tolerant on purpose: the real output has one ``package:<id>`` per line, and
+    a shell that prepends noise (adb banners, warnings) must not lose the list.
+    Duplicates are collapsed, order preserved.
+    """
+    if not output:
+        return []
+    seen: set[str] = set()
+    packages: list[str] = []
+    for match in _PACKAGE_LINE_RE.finditer(output):
+        package = match.group("package")
+        if package not in seen:
+            seen.add(package)
+            packages.append(package)
+    return packages
+
+
+def parse_active_launcher(output: str | None) -> str | None:
+    """The active HOME package from ``cmd package resolve-activity --brief``.
+
+    Android prints a verbose intent header and then a single
+    ``package/activity`` line; only the last component-looking line is the
+    answer. Returns None when nothing resolved (a device with no launcher, or a
+    command that produced no output) — the caller treats that as "no launcher
+    to add" rather than as a failure.
+    """
+    if not output:
+        return None
+    packages = _COMPONENT_RE.findall(output)
+    for package in reversed(packages):
+        if package not in _LAUNCHER_NOISE:
+            return package
+    return None
+
+
+def installed_packages(user_output: str | None, launcher_output: str | None) -> list[str]:
+    """The discovered package ids: user apps first, then the active launcher.
+
+    The launcher goes last so a source list built from this keeps the user's own
+    apps at the top, and it is de-duplicated because a launcher CAN be a
+    third-party package (a replacement TV launcher installed from the store).
+    """
+    packages = parse_package_list(user_output)
+    launcher = parse_active_launcher(launcher_output)
+    if launcher and launcher not in packages:
+        packages.append(launcher)
+    return packages
+
+
+def icon_for_package(package: str, curated: dict[str, str] | None = None,
+                     generic: str = "mdi:television") -> str:
+    """A best-effort MDI icon for a package, never a non-string (t57).
+
+    HEURISTIC, and labelled as such: the icon is looked up in a curated
+    package -> MDI map, and anything unknown gets the generic fallback. There is
+    no device query behind this because there cannot be one — ``pm dump`` does
+    not print the app's icon resource, and resolving an extracted APK's bitmap
+    would need code the app itself runs. The user's own icon column (a picture
+    URL or a ``camera.*`` entity) is what ``entity_picture`` consumes, and it
+    outranks this.
+
+    Returns a string in every case: the UI is never handed None or a dict.
+    """
+    if not package:
+        return generic
+    table = curated if curated is not None else {}
+    return table.get(package) or generic
+
+
+def is_launchable(package: str) -> bool:
+    """Cheap sanity filter for a package id.
+
+    Not a real Android query: a package id is dotted and non-empty. The filter
+    exists so a malformed line cannot become a table row or a source entry.
+    """
+    return bool(package) and "." in package and all(
+        part.isalnum() or part in ("_", "-") for part in package.split(".")
+    )