feat: add thermostat climate entity wiring BME280 sensor to relay outputs

firmware/components/climate.yaml

@@ -1 +1,44 @@
-# placeholder — see task 3/4/5/6
+climate:
+  - platform: thermostat
+    name: "Thermostat"
+    id: main_thermostat
+    sensor: bme280_temperature
+    min_idle_time: 30s
+    min_heating_off_time: 300s
+    min_heating_run_time: 300s
+    min_cooling_off_time: 300s
+    min_cooling_run_time: 300s
+    heat_deadband: 0.5
+    cool_deadband: 0.5
+    default_preset: home
+    preset:
+      - name: home
+        default_target_temperature_low: 20 °C
+        default_target_temperature_high: 24 °C
+      - name: away
+        default_target_temperature_low: 16 °C
+        default_target_temperature_high: 28 °C
+    heat_action:
+      - switch.turn_on: relay_fan
+      - switch.turn_on: relay_heat1
+    heat_mode:
+      - switch.turn_off: relay_cool1
+      - switch.turn_off: relay_cool2
+    cool_action:
+      - switch.turn_on: relay_fan
+      - switch.turn_on: relay_cool1
+    cool_mode:
+      - switch.turn_off: relay_heat1
+      - switch.turn_off: relay_heat2
+    idle_action:
+      - switch.turn_off: relay_fan
+      - switch.turn_off: relay_heat1
+      - switch.turn_off: relay_heat2
+      - switch.turn_off: relay_cool1
+      - switch.turn_off: relay_cool2
+    off_mode:
+      - switch.turn_off: relay_fan
+      - switch.turn_off: relay_heat1
+      - switch.turn_off: relay_heat2
+      - switch.turn_off: relay_cool1
+      - switch.turn_off: relay_cool2