Implement ingest-service: MQTT -> ClickHouse (batched) + RabbitMQ event

Subscribes to devices/+/telemetry, validates payloads, buffers writes into
ClickHouse (flush on size or interval), and emits a per-reading event on
RabbitMQ for rule-engine-service to consume later. Adds the initial Postgres
and ClickHouse schema migrations, a Dockerfile, and wires the service into
docker-compose. Verified end-to-end via docker compose + mosquitto_pub: row
lands in ClickHouse and the event reaches the telemetry.new_reading queue.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

docker-compose.yml

@@ -55,6 +55,11 @@ services:
       - ./migrations/clickhouse:/docker-entrypoint-initdb.d:ro
     networks:
       - home-automation
+    healthcheck:
+      test: ["CMD", "clickhouse-client", "--query", "SELECT 1"]
+      interval: 5s
+      timeout: 5s
+      retries: 10
     restart: unless-stopped
 
   redis:
@@ -86,6 +91,31 @@ services:
       retries: 10
     restart: unless-stopped
 
-  # App services (ingest-service, device-control-service, rule-engine-service,
+  ingest-service:
+    build: ./services/ingest-service
+    environment:
+      MQTT_HOST: mosquitto
+      MQTT_PORT: 1883
+      CLICKHOUSE_HOST: clickhouse
+      CLICKHOUSE_NATIVE_PORT: 9000
+      CLICKHOUSE_DB: ${CLICKHOUSE_DB}
+      CLICKHOUSE_USER: ${CLICKHOUSE_USER}
+      CLICKHOUSE_PASSWORD: ${CLICKHOUSE_PASSWORD}
+      RABBITMQ_HOST: rabbitmq
+      RABBITMQ_PORT: 5672
+      RABBITMQ_USER: ${RABBITMQ_USER}
+      RABBITMQ_PASSWORD: ${RABBITMQ_PASSWORD}
+    depends_on:
+      mosquitto:
+        condition: service_started
+      clickhouse:
+        condition: service_healthy
+      rabbitmq:
+        condition: service_healthy
+    networks:
+      - home-automation
+    restart: unless-stopped
+
+  # Remaining app services (device-control-service, rule-engine-service,
   # health-check-service, esp32-emulator, laravel-app) are added here as they
   # get implemented — see services/*/README.md for the plan for each one.