Remove hardcoded HA entity IDs from include files; expose all as substitution variables

[Copilot]

The package had Italian-installation-specific HA entity IDs hardcoded throughout include/, making it impossible to reuse without forking. All sensor/actuator entity IDs, room identifiers, display names, and scene references are now substitution variables.

New substitution variables (main.yaml / dev-sdl.yaml)

Group	Variables
Rooms 1–4	room{N}_id, room{N}_name, room{N}_ha_temperature_sensor, room{N}_ha_humidity_sensor, room{N}_ha_window_contact_sensor, room{N}_ha_floor_heating_switch, room{N}_ha_cover
Temp settings 1–2	temp_setting{N}_id, temp_setting{N}_label, temp_setting{N}_icon, temp_setting{N}_ha_sensor
Target temp	ha_temperature_target_sensor
Scenes 1–2	scene{N}_entity_id, scene{N}_name

Generic placeholders are the defaults; real values belong only in consumer configs.

include/ changes

• sensors.yaml — room sensor packages + temp setting + target sensor now reference substitution vars via quoted "${...}" in flow-mapping vars blocks
• sensors_temperature_target.yaml — internal ESPHome IDs (sensor_temp_${temp_setting1_id}) and LVGL label IDs (lbl_target_temp_heating_${room{N}_id}) use substitution vars
• lvgl_tab_rooms.yaml, lvgl_tab_heating_details.yaml, lvgl_tab_covers.yaml — room boxes rendered in consistent room1→room4 order using substitution vars
• lvgl_tab_heating_set_temp.yaml — temp setting IDs, labels, icons, and HA input_number entity IDs via substitution vars
• lvgl_tab_scenes.yaml — scene entity IDs and button labels via substitution vars

example-instance.yaml

All original Italian-installation entity IDs moved here as vars overrides:

vars:
  room1_id: "bagno_p1"
  room1_ha_temperature_sensor: "sensor.lumi_sensore_ambientale_bagno_p1_temperature"
  room1_ha_cover: "cover.tapparella_bagno_piano_primo"
  # ... all 4 rooms, 2 temp settings, target sensor, 2 scenes
  scene1_entity_id: "scene.tapparelle_aperte_max"