Add the morning summary blueprint

Iterates present children from the Feature 10 presence sensors, lists
what each owes today from the remaining sensor, omits absent children
entirely. Blueprint inputs (time, notify service, send toggle); the
notify target is the household's choice, never hard-coded. PyYAML and
Jinja2 join the dev-only dependencies for blueprint template tests.

pyproject.toml

@@ -8,8 +8,10 @@ dependencies = []
 
 [dependency-groups]
 dev = [
+    "jinja2>=3",
     "pytest>=8.0.0",
     "pytest-asyncio>=0.24",
+    "pyyaml>=6",
     "voluptuous>=0.14",
 ]