feat(measurements): accept indoor CO2, temperature and humidity

Room climate from a home automation system gets three types of its own:
INDOOR_CO2 (ppm), INDOOR_TEMPERATURE (celsius, shown in Fahrenheit for
imperial readers) and INDOOR_HUMIDITY (percent). They arrive through the
existing ingest token (measurements:write, source EXTERNAL), sit in the
environment cluster beside daylight, and the daily rollup carries their
mean, low and high like any spot reading. They never mix with the body
temperatures or with the outdoor environment channels.

The Home Assistant page documents the three types, a rest_command that
sends a room as one request, a single-room automation, and an
importable blueprint (docs/integrations/blueprints) that skips sensors
reporting unknown or non-numeric states, converts Fahrenheit, and
stamps readings to the minute so a retried push is refused rather than
written twice.

docs/integrations/blueprints/healthlog-room-climate.yaml

@@ -0,0 +1,93 @@
+# Push a room's CO2, temperature and humidity to HealthLog every few minutes.
+#
+# Needs the `healthlog_room_climate` rest_command from
+# docs/integrations/home-assistant.md ("Room climate") and a measurement
+# ingest token. Every sensor is optional; a sensor that reports `unknown`,
+# `unavailable` or a non-number is left out of that push, and a push with
+# nothing left is skipped. Temperatures in °F are converted to °C.
+blueprint:
+  name: HealthLog room climate
+  description: >-
+    Sends indoor CO2 (ppm), temperature (°C) and relative humidity (%) to
+    HealthLog through a measurement ingest token. HealthLog keeps each
+    reading and shows the day's mean, low and high.
+  domain: automation
+  source_url: https://github.com/MBombeck/HealthLog/blob/main/docs/integrations/blueprints/healthlog-room-climate.yaml
+  input:
+    co2_sensor:
+      name: CO2 sensor
+      description: A sensor reporting carbon dioxide in ppm.
+      default: ""
+      selector:
+        entity:
+          domain: sensor
+          device_class: carbon_dioxide
+    temperature_sensor:
+      name: Temperature sensor
+      description: A sensor reporting the room temperature (°C or °F).
+      default: ""
+      selector:
+        entity:
+          domain: sensor
+          device_class: temperature
+    humidity_sensor:
+      name: Humidity sensor
+      description: A sensor reporting relative humidity in %.
+      default: ""
+      selector:
+        entity:
+          domain: sensor
+          device_class: humidity
+    interval_minutes:
+      name: Interval
+      description: Minutes between pushes. 15 is plenty for a daily picture.
+      default: 15
+      selector:
+        number:
+          min: 5
+          max: 60
+          step: 5
+          unit_of_measurement: min
+
+mode: single
+
+variables:
+  co2_sensor: !input co2_sensor
+  temperature_sensor: !input temperature_sensor
+  humidity_sensor: !input humidity_sensor
+  interval_minutes: !input interval_minutes
+  # A list of readings (Home Assistant keeps a rendered list a list).
+  readings: >-
+    {% set at = now().replace(second=0, microsecond=0).isoformat() %}
+    {% set ns = namespace(items=[]) %}
+    {% for type, entity in [
+      ('INDOOR_CO2', co2_sensor),
+      ('INDOOR_TEMPERATURE', temperature_sensor),
+      ('INDOOR_HUMIDITY', humidity_sensor)
+    ] %}
+      {% if entity and is_number(states(entity)) %}
+        {% set v = states(entity) | float %}
+        {% if type == 'INDOOR_TEMPERATURE'
+              and state_attr(entity, 'unit_of_measurement') == '°F' %}
+          {% set v = ((v - 32) * 5 / 9) | round(2) %}
+        {% endif %}
+        {% set ns.items = ns.items
+          + [{'type': type, 'value': v, 'measuredAt': at}] %}
+      {% endif %}
+    {% endfor %}
+    {{ ns.items }}
+
+trigger:
+  - platform: time_pattern
+    minutes: "/5"
+
+condition:
+  - condition: template
+    value_template: >-
+      {{ now().minute % (interval_minutes | int(15)) == 0
+         and readings | count > 0 }}
+
+action:
+  - service: rest_command.healthlog_room_climate
+    data:
+      readings: "{{ readings }}"