Add per-child all-done and present-today binary sensors

all_done is on exactly when the child owed quests today and owes none
remaining (a zero-quest day stays off so celebrations never fire on
an empty day); present_today mirrors the presence engine's answer
for the HA-local date.

tests/test_const.py

@@ -28,10 +28,10 @@ def test_logger() -> None:
 
 
 def test_platforms() -> None:
-    """Verify PLATFORMS is defined as the sensor platform list."""
+    """Verify PLATFORMS is defined as the sensor + binary_sensor list."""
     assert hasattr(const, "PLATFORMS")
     assert isinstance(const.PLATFORMS, list)
-    assert const.PLATFORMS == ["sensor"]
+    assert const.PLATFORMS == ["sensor", "binary_sensor"]
 
 
 def test_sqlite_db_filename() -> None: